<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/kernel/sched/fair.c, branch v6.11</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge branch 'sched/urgent' into sched/core, to pick up fixes and refresh the branch</title>
<updated>2024-07-11T08:42:33+00:00</updated>
<author>
<name>Ingo Molnar</name>
<email>mingo@kernel.org</email>
</author>
<published>2024-07-11T08:42:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=011b1134b82c2750d83a299a1369c678845de45a'/>
<id>011b1134b82c2750d83a299a1369c678845de45a</id>
<content type='text'>
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sched/fair: set_load_weight() must also call reweight_task() for SCHED_IDLE tasks</title>
<updated>2024-07-04T13:59:52+00:00</updated>
<author>
<name>Tejun Heo</name>
<email>tj@kernel.org</email>
</author>
<published>2024-06-26T01:29:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d329605287020c3d1c3b0dadc63d8208e7251382'/>
<id>d329605287020c3d1c3b0dadc63d8208e7251382</id>
<content type='text'>
When a task's weight is being changed, set_load_weight() is called with
@update_load set. As weight changes aren't trivial for the fair class,
set_load_weight() calls fair.c::reweight_task() for fair class tasks.

However, set_load_weight() first tests task_has_idle_policy() on entry and
skips calling reweight_task() for SCHED_IDLE tasks. This is buggy as
SCHED_IDLE tasks are just fair tasks with a very low weight and they would
incorrectly skip load, vlag and position updates.

Fix it by updating reweight_task() to take struct load_weight as idle weight
can't be expressed with prio and making set_load_weight() call
reweight_task() for SCHED_IDLE tasks too when @update_load is set.

Fixes: 9059393e4ec1 ("sched/fair: Use reweight_entity() for set_user_nice()")
Suggested-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: stable@vger.kernel.org # v4.15+
Link: http://lkml.kernel.org/r/20240624102331.GI31592@noisy.programming.kicks-ass.net
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When a task's weight is being changed, set_load_weight() is called with
@update_load set. As weight changes aren't trivial for the fair class,
set_load_weight() calls fair.c::reweight_task() for fair class tasks.

However, set_load_weight() first tests task_has_idle_policy() on entry and
skips calling reweight_task() for SCHED_IDLE tasks. This is buggy as
SCHED_IDLE tasks are just fair tasks with a very low weight and they would
incorrectly skip load, vlag and position updates.

Fix it by updating reweight_task() to take struct load_weight as idle weight
can't be expressed with prio and making set_load_weight() call
reweight_task() for SCHED_IDLE tasks too when @update_load is set.

Fixes: 9059393e4ec1 ("sched/fair: Use reweight_entity() for set_user_nice()")
Suggested-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: stable@vger.kernel.org # v4.15+
Link: http://lkml.kernel.org/r/20240624102331.GI31592@noisy.programming.kicks-ass.net
</pre>
</div>
</content>
</entry>
<entry>
<title>Revert "sched/fair: Make sure to try to detach at least one movable task"</title>
<updated>2024-07-01T11:01:43+00:00</updated>
<author>
<name>Josh Don</name>
<email>joshdon@google.com</email>
</author>
<published>2024-06-20T21:44:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=2feab2492deb2f14f9675dd6388e9e2bf669c27a'/>
<id>2feab2492deb2f14f9675dd6388e9e2bf669c27a</id>
<content type='text'>
This reverts commit b0defa7ae03ecf91b8bfd10ede430cff12fcbd06.

b0defa7ae03ec changed the load balancing logic to ignore env.max_loop if
all tasks examined to that point were pinned. The goal of the patch was
to make it more likely to be able to detach a task buried in a long list
of pinned tasks. However, this has the unfortunate side effect of
creating an O(n) iteration in detach_tasks(), as we now must fully
iterate every task on a cpu if all or most are pinned. Since this load
balance code is done with rq lock held, and often in softirq context, it
is very easy to trigger hard lockups. We observed such hard lockups with
a user who affined O(10k) threads to a single cpu.

When I discussed this with Vincent he initially suggested that we keep
the limit on the number of tasks to detach, but increase the number of
tasks we can search. However, after some back and forth on the mailing
list, he recommended we instead revert the original patch, as it seems
likely no one was actually getting hit by the original issue.

Fixes: b0defa7ae03e ("sched/fair: Make sure to try to detach at least one movable task")
Signed-off-by: Josh Don &lt;joshdon@google.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Link: https://lore.kernel.org/r/20240620214450.316280-1-joshdon@google.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This reverts commit b0defa7ae03ecf91b8bfd10ede430cff12fcbd06.

b0defa7ae03ec changed the load balancing logic to ignore env.max_loop if
all tasks examined to that point were pinned. The goal of the patch was
to make it more likely to be able to detach a task buried in a long list
of pinned tasks. However, this has the unfortunate side effect of
creating an O(n) iteration in detach_tasks(), as we now must fully
iterate every task on a cpu if all or most are pinned. Since this load
balance code is done with rq lock held, and often in softirq context, it
is very easy to trigger hard lockups. We observed such hard lockups with
a user who affined O(10k) threads to a single cpu.

When I discussed this with Vincent he initially suggested that we keep
the limit on the number of tasks to detach, but increase the number of
tasks we can search. However, after some back and forth on the mailing
list, he recommended we instead revert the original patch, as it seems
likely no one was actually getting hit by the original issue.

Fixes: b0defa7ae03e ("sched/fair: Make sure to try to detach at least one movable task")
Signed-off-by: Josh Don &lt;joshdon@google.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Link: https://lore.kernel.org/r/20240620214450.316280-1-joshdon@google.com
</pre>
</div>
</content>
</entry>
<entry>
<title>sched/balance: Skip unnecessary updates to idle load balancer's flags</title>
<updated>2024-06-05T13:52:36+00:00</updated>
<author>
<name>Tim Chen</name>
<email>tim.c.chen@linux.intel.com</email>
</author>
<published>2024-05-31T20:54:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=f90cc919f9e5cbfcd0b952290c57ef1317f4e91e'/>
<id>f90cc919f9e5cbfcd0b952290c57ef1317f4e91e</id>
<content type='text'>
We observed that the overhead on trigger_load_balance(), now renamed
sched_balance_trigger(), has risen with a system's core counts.

For an OLTP workload running 6.8 kernel on a 2 socket x86 systems
having 96 cores/socket, we saw that 0.7% cpu cycles are spent in
trigger_load_balance(). On older systems with fewer cores/socket, this
function's overhead was less than 0.1%.

The cause of this overhead was that there are multiple cpus calling
kick_ilb(flags), updating the balancing work needed to a common idle
load balancer cpu. The ilb_cpu's flags field got updated unconditionally
with atomic_fetch_or().  The atomic read and writes to ilb_cpu's flags
causes much cache bouncing and cpu cycles overhead. This is seen in the
annotated profile below.

             kick_ilb():
             if (ilb_cpu &lt; 0)
               test   %r14d,%r14d
             ↑ js     6c
             flags = atomic_fetch_or(flags, nohz_flags(ilb_cpu));
               mov    $0x2d600,%rdi
               movslq %r14d,%r8
               mov    %rdi,%rdx
               add    -0x7dd0c3e0(,%r8,8),%rdx
             arch_atomic_read():
  0.01         mov    0x64(%rdx),%esi
 35.58         add    $0x64,%rdx
             arch_atomic_fetch_or():

             static __always_inline int arch_atomic_fetch_or(int i, atomic_t *v)
             {
             int val = arch_atomic_read(v);

             do { } while (!arch_atomic_try_cmpxchg(v, &amp;val, val | i));
  0.03  157:   mov    %r12d,%ecx
             arch_atomic_try_cmpxchg():
             return arch_try_cmpxchg(&amp;v-&gt;counter, old, new);
  0.00         mov    %esi,%eax
             arch_atomic_fetch_or():
             do { } while (!arch_atomic_try_cmpxchg(v, &amp;val, val | i));
               or     %esi,%ecx
             arch_atomic_try_cmpxchg():
             return arch_try_cmpxchg(&amp;v-&gt;counter, old, new);
  0.01         lock   cmpxchg %ecx,(%rdx)
 42.96       ↓ jne    2d2
             kick_ilb():

With instrumentation, we found that 81% of the updates do not result in
any change in the ilb_cpu's flags.  That is, multiple cpus are asking
the ilb_cpu to do the same things over and over again, before the ilb_cpu
has a chance to run NOHZ load balance.

Skip updates to ilb_cpu's flags if no new work needs to be done.
Such updates do not change ilb_cpu's NOHZ flags.  This requires an extra
atomic read but it is less expensive than frequent unnecessary atomic
updates that generate cache bounces.

We saw that on the OLTP workload, cpu cycles from trigger_load_balance()
(or sched_balance_trigger()) got reduced from 0.7% to 0.2%.

Signed-off-by: Tim Chen &lt;tim.c.chen@linux.intel.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Chen Yu &lt;yu.c.chen@intel.com&gt;
Reviewed-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Link: https://lore.kernel.org/r/20240531205452.65781-1-tim.c.chen@linux.intel.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We observed that the overhead on trigger_load_balance(), now renamed
sched_balance_trigger(), has risen with a system's core counts.

For an OLTP workload running 6.8 kernel on a 2 socket x86 systems
having 96 cores/socket, we saw that 0.7% cpu cycles are spent in
trigger_load_balance(). On older systems with fewer cores/socket, this
function's overhead was less than 0.1%.

The cause of this overhead was that there are multiple cpus calling
kick_ilb(flags), updating the balancing work needed to a common idle
load balancer cpu. The ilb_cpu's flags field got updated unconditionally
with atomic_fetch_or().  The atomic read and writes to ilb_cpu's flags
causes much cache bouncing and cpu cycles overhead. This is seen in the
annotated profile below.

             kick_ilb():
             if (ilb_cpu &lt; 0)
               test   %r14d,%r14d
             ↑ js     6c
             flags = atomic_fetch_or(flags, nohz_flags(ilb_cpu));
               mov    $0x2d600,%rdi
               movslq %r14d,%r8
               mov    %rdi,%rdx
               add    -0x7dd0c3e0(,%r8,8),%rdx
             arch_atomic_read():
  0.01         mov    0x64(%rdx),%esi
 35.58         add    $0x64,%rdx
             arch_atomic_fetch_or():

             static __always_inline int arch_atomic_fetch_or(int i, atomic_t *v)
             {
             int val = arch_atomic_read(v);

             do { } while (!arch_atomic_try_cmpxchg(v, &amp;val, val | i));
  0.03  157:   mov    %r12d,%ecx
             arch_atomic_try_cmpxchg():
             return arch_try_cmpxchg(&amp;v-&gt;counter, old, new);
  0.00         mov    %esi,%eax
             arch_atomic_fetch_or():
             do { } while (!arch_atomic_try_cmpxchg(v, &amp;val, val | i));
               or     %esi,%ecx
             arch_atomic_try_cmpxchg():
             return arch_try_cmpxchg(&amp;v-&gt;counter, old, new);
  0.01         lock   cmpxchg %ecx,(%rdx)
 42.96       ↓ jne    2d2
             kick_ilb():

With instrumentation, we found that 81% of the updates do not result in
any change in the ilb_cpu's flags.  That is, multiple cpus are asking
the ilb_cpu to do the same things over and over again, before the ilb_cpu
has a chance to run NOHZ load balance.

Skip updates to ilb_cpu's flags if no new work needs to be done.
Such updates do not change ilb_cpu's NOHZ flags.  This requires an extra
atomic read but it is less expensive than frequent unnecessary atomic
updates that generate cache bounces.

We saw that on the OLTP workload, cpu cycles from trigger_load_balance()
(or sched_balance_trigger()) got reduced from 0.7% to 0.2%.

Signed-off-by: Tim Chen &lt;tim.c.chen@linux.intel.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Chen Yu &lt;yu.c.chen@intel.com&gt;
Reviewed-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Link: https://lore.kernel.org/r/20240531205452.65781-1-tim.c.chen@linux.intel.com
</pre>
</div>
</content>
</entry>
<entry>
<title>sched: Fix spelling in comments</title>
<updated>2024-05-27T15:00:21+00:00</updated>
<author>
<name>Ingo Molnar</name>
<email>mingo@kernel.org</email>
</author>
<published>2024-05-27T14:54:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=402de7fc880fef055bc984957454b532987e9ad0'/>
<id>402de7fc880fef055bc984957454b532987e9ad0</id>
<content type='text'>
Do a spell-checking pass.

Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Do a spell-checking pass.

Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'sched-urgent-2024-05-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2024-05-19T18:38:15+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-05-19T18:38:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=8dde191aabba42e9c16c8d9c853a72a062db27ee'/>
<id>8dde191aabba42e9c16c8d9c853a72a062db27ee</id>
<content type='text'>
Pull scheduler fixes from Ingo Molnar:

 - Fix a sched_balance_newidle setting bug

 - Fix bug in the setting of /sys/fs/cgroup/test/cpu.max.burst

 - Fix variable-shadowing build warning

 - Extend sched-domains debug output

 - Fix documentation

 - Fix comments

* tag 'sched-urgent-2024-05-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Fix incorrect initialization of the 'burst' parameter in cpu_max_write()
  sched/fair: Remove stale FREQUENCY_UTIL comment
  sched/fair: Fix initial util_avg calculation
  docs: cgroup-v1: Clarify that domain levels are system-specific
  sched/debug: Dump domains' level
  sched/fair: Allow disabling sched_balance_newidle with sched_relax_domain_level
  arch/topology: Fix variable naming to avoid shadowing
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull scheduler fixes from Ingo Molnar:

 - Fix a sched_balance_newidle setting bug

 - Fix bug in the setting of /sys/fs/cgroup/test/cpu.max.burst

 - Fix variable-shadowing build warning

 - Extend sched-domains debug output

 - Fix documentation

 - Fix comments

* tag 'sched-urgent-2024-05-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Fix incorrect initialization of the 'burst' parameter in cpu_max_write()
  sched/fair: Remove stale FREQUENCY_UTIL comment
  sched/fair: Fix initial util_avg calculation
  docs: cgroup-v1: Clarify that domain levels are system-specific
  sched/debug: Dump domains' level
  sched/fair: Allow disabling sched_balance_newidle with sched_relax_domain_level
  arch/topology: Fix variable naming to avoid shadowing
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'sysctl-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl</title>
<updated>2024-05-18T00:31:24+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-05-18T00:31:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=91b6163be404e36baea39fc978e4739fd0448ebd'/>
<id>91b6163be404e36baea39fc978e4739fd0448ebd</id>
<content type='text'>
Pull sysctl updates from Joel Granados:

 - Remove sentinel elements from ctl_table structs in kernel/*

   Removing sentinels in ctl_table arrays reduces the build time size
   and runtime memory consumed by ~64 bytes per array. Removals for
   net/, io_uring/, mm/, ipc/ and security/ are set to go into mainline
   through their respective subsystems making the next release the most
   likely place where the final series that removes the check for
   proc_name == NULL will land.

   This adds to removals already in arch/, drivers/ and fs/.

 - Adjust ctl_table definitions and references to allow constification
     - Remove unused ctl_table function arguments
     - Move non-const elements from ctl_table to ctl_table_header
     - Make ctl_table pointers const in ctl_table_root structure

   Making the static ctl_table structs const will increase safety by
   keeping the pointers to proc_handler functions in .rodata. Though no
   ctl_tables where made const in this PR, the ground work for making
   that possible has started with these changes sent by Thomas
   Weißschuh.

* tag 'sysctl-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl:
  sysctl: drop now unnecessary out-of-bounds check
  sysctl: move sysctl type to ctl_table_header
  sysctl: drop sysctl_is_perm_empty_ctl_table
  sysctl: treewide: constify argument ctl_table_root::permissions(table)
  sysctl: treewide: drop unused argument ctl_table_root::set_ownership(table)
  bpf: Remove the now superfluous sentinel elements from ctl_table array
  delayacct: Remove the now superfluous sentinel elements from ctl_table array
  kprobes: Remove the now superfluous sentinel elements from ctl_table array
  printk: Remove the now superfluous sentinel elements from ctl_table array
  scheduler: Remove the now superfluous sentinel elements from ctl_table array
  seccomp: Remove the now superfluous sentinel elements from ctl_table array
  timekeeping: Remove the now superfluous sentinel elements from ctl_table array
  ftrace: Remove the now superfluous sentinel elements from ctl_table array
  umh: Remove the now superfluous sentinel elements from ctl_table array
  kernel misc: Remove the now superfluous sentinel elements from ctl_table array
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull sysctl updates from Joel Granados:

 - Remove sentinel elements from ctl_table structs in kernel/*

   Removing sentinels in ctl_table arrays reduces the build time size
   and runtime memory consumed by ~64 bytes per array. Removals for
   net/, io_uring/, mm/, ipc/ and security/ are set to go into mainline
   through their respective subsystems making the next release the most
   likely place where the final series that removes the check for
   proc_name == NULL will land.

   This adds to removals already in arch/, drivers/ and fs/.

 - Adjust ctl_table definitions and references to allow constification
     - Remove unused ctl_table function arguments
     - Move non-const elements from ctl_table to ctl_table_header
     - Make ctl_table pointers const in ctl_table_root structure

   Making the static ctl_table structs const will increase safety by
   keeping the pointers to proc_handler functions in .rodata. Though no
   ctl_tables where made const in this PR, the ground work for making
   that possible has started with these changes sent by Thomas
   Weißschuh.

* tag 'sysctl-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl:
  sysctl: drop now unnecessary out-of-bounds check
  sysctl: move sysctl type to ctl_table_header
  sysctl: drop sysctl_is_perm_empty_ctl_table
  sysctl: treewide: constify argument ctl_table_root::permissions(table)
  sysctl: treewide: drop unused argument ctl_table_root::set_ownership(table)
  bpf: Remove the now superfluous sentinel elements from ctl_table array
  delayacct: Remove the now superfluous sentinel elements from ctl_table array
  kprobes: Remove the now superfluous sentinel elements from ctl_table array
  printk: Remove the now superfluous sentinel elements from ctl_table array
  scheduler: Remove the now superfluous sentinel elements from ctl_table array
  seccomp: Remove the now superfluous sentinel elements from ctl_table array
  timekeeping: Remove the now superfluous sentinel elements from ctl_table array
  ftrace: Remove the now superfluous sentinel elements from ctl_table array
  umh: Remove the now superfluous sentinel elements from ctl_table array
  kernel misc: Remove the now superfluous sentinel elements from ctl_table array
</pre>
</div>
</content>
</entry>
<entry>
<title>sched/fair: Remove stale FREQUENCY_UTIL comment</title>
<updated>2024-05-17T07:51:54+00:00</updated>
<author>
<name>Christian Loehle</name>
<email>christian.loehle@arm.com</email>
</author>
<published>2024-03-05T15:18:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=7cb7fb5b49399fc59f1c44686d82c0df0776c8c6'/>
<id>7cb7fb5b49399fc59f1c44686d82c0df0776c8c6</id>
<content type='text'>
On 05/03/2024 15:05, Vincent Guittot wrote:

I'm fine with either and that was my first thought here, too, but it did seem like
the comment was mostly placed there to justify the 'unexpected' high utilization
when explicitly passing FREQUENCY_UTIL and the need to clamp it then.
So removing did feel slightly more natural to me anyway.

So alternatively:

From: Christian Loehle &lt;christian.loehle@arm.com&gt;
Date: Tue, 5 Mar 2024 09:34:41 +0000
Subject: [PATCH] sched/fair: Remove stale FREQUENCY_UTIL mention

effective_cpu_util() flags were removed, so remove mentioning of the
flag.

commit 9c0b4bb7f6303 ("sched/cpufreq: Rework schedutil governor performance estimation")
reworked effective_cpu_util() removing enum cpu_util_type. Modify the
comment accordingly.

Signed-off-by: Christian Loehle &lt;christian.loehle@arm.com&gt;
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Reviewed-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Link: https://lore.kernel.org/r/0e2833ee-0939-44e0-82a2-520a585a0153@arm.com
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<pre>
On 05/03/2024 15:05, Vincent Guittot wrote:

I'm fine with either and that was my first thought here, too, but it did seem like
the comment was mostly placed there to justify the 'unexpected' high utilization
when explicitly passing FREQUENCY_UTIL and the need to clamp it then.
So removing did feel slightly more natural to me anyway.

So alternatively:

From: Christian Loehle &lt;christian.loehle@arm.com&gt;
Date: Tue, 5 Mar 2024 09:34:41 +0000
Subject: [PATCH] sched/fair: Remove stale FREQUENCY_UTIL mention

effective_cpu_util() flags were removed, so remove mentioning of the
flag.

commit 9c0b4bb7f6303 ("sched/cpufreq: Rework schedutil governor performance estimation")
reworked effective_cpu_util() removing enum cpu_util_type. Modify the
comment accordingly.

Signed-off-by: Christian Loehle &lt;christian.loehle@arm.com&gt;
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Reviewed-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Link: https://lore.kernel.org/r/0e2833ee-0939-44e0-82a2-520a585a0153@arm.com
</pre>
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</entry>
<entry>
<title>sched/fair: Fix initial util_avg calculation</title>
<updated>2024-05-17T07:49:44+00:00</updated>
<author>
<name>Dawei Li</name>
<email>daweilics@gmail.com</email>
</author>
<published>2024-03-15T01:59:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=72bffbf57c5247ac6146d1103ef42e9f8d094bc8'/>
<id>72bffbf57c5247ac6146d1103ef42e9f8d094bc8</id>
<content type='text'>
Change se-&gt;load.weight to se_weight(se) in the calculation for the
initial util_avg to avoid unnecessarily inflating the util_avg by 1024
times.

The reason is that se-&gt;load.weight has the unit/scale as the scaled-up
load, while cfs_rg-&gt;avg.load_avg has the unit/scale as the true task
weight (as mapped directly from the task's nice/priority value). With
CONFIG_32BIT, the scaled-up load is equal to the true task weight. With
CONFIG_64BIT, the scaled-up load is 1024 times the true task weight.
Thus, the current code may inflate the util_avg by 1024 times. The
follow-up capping will not allow the util_avg value to go wild. But the
calculation should have the correct logic.

Signed-off-by: Dawei Li &lt;daweilics@gmail.com&gt;
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Reviewed-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Reviewed-by: Vishal Chourasia &lt;vishalc@linux.ibm.com&gt;
Link: https://lore.kernel.org/r/20240315015916.21545-1-daweilics@gmail.com
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<pre>
Change se-&gt;load.weight to se_weight(se) in the calculation for the
initial util_avg to avoid unnecessarily inflating the util_avg by 1024
times.

The reason is that se-&gt;load.weight has the unit/scale as the scaled-up
load, while cfs_rg-&gt;avg.load_avg has the unit/scale as the true task
weight (as mapped directly from the task's nice/priority value). With
CONFIG_32BIT, the scaled-up load is equal to the true task weight. With
CONFIG_64BIT, the scaled-up load is 1024 times the true task weight.
Thus, the current code may inflate the util_avg by 1024 times. The
follow-up capping will not allow the util_avg value to go wild. But the
calculation should have the correct logic.

Signed-off-by: Dawei Li &lt;daweilics@gmail.com&gt;
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Reviewed-by: Vincent Guittot &lt;vincent.guittot@linaro.org&gt;
Reviewed-by: Vishal Chourasia &lt;vishalc@linux.ibm.com&gt;
Link: https://lore.kernel.org/r/20240315015916.21545-1-daweilics@gmail.com
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'sched-core-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2024-05-14T00:18:51+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-05-14T00:18:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=6e5a0c30b616bfff6926ecca5d88e3d06e6bf79a'/>
<id>6e5a0c30b616bfff6926ecca5d88e3d06e6bf79a</id>
<content type='text'>
Pull scheduler updates from Ingo Molnar:

 - Add cpufreq pressure feedback for the scheduler

 - Rework misfit load-balancing wrt affinity restrictions

 - Clean up and simplify the code around ::overutilized and
   ::overload access.

 - Simplify sched_balance_newidle()

 - Bump SCHEDSTAT_VERSION to 16 due to a cleanup of CPU_MAX_IDLE_TYPES
   handling that changed the output.

 - Rework &amp; clean up &lt;asm/vtime.h&gt; interactions wrt arch_vtime_task_switch()

 - Reorganize, clean up and unify most of the higher level
   scheduler balancing function names around the sched_balance_*()
   prefix

 - Simplify the balancing flag code (sched_balance_running)

 - Miscellaneous cleanups &amp; fixes

* tag 'sched-core-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (50 commits)
  sched/pelt: Remove shift of thermal clock
  sched/cpufreq: Rename arch_update_thermal_pressure() =&gt; arch_update_hw_pressure()
  thermal/cpufreq: Remove arch_update_thermal_pressure()
  sched/cpufreq: Take cpufreq feedback into account
  cpufreq: Add a cpufreq pressure feedback for the scheduler
  sched/fair: Fix update of rd-&gt;sg_overutilized
  sched/vtime: Do not include &lt;asm/vtime.h&gt; header
  s390/irq,nmi: Include &lt;asm/vtime.h&gt; header directly
  s390/vtime: Remove unused __ARCH_HAS_VTIME_TASK_SWITCH leftover
  sched/vtime: Get rid of generic vtime_task_switch() implementation
  sched/vtime: Remove confusing arch_vtime_task_switch() declaration
  sched/balancing: Simplify the sg_status bitmask and use separate -&gt;overloaded and -&gt;overutilized flags
  sched/fair: Rename set_rd_overutilized_status() to set_rd_overutilized()
  sched/fair: Rename SG_OVERLOAD to SG_OVERLOADED
  sched/fair: Rename {set|get}_rd_overload() to {set|get}_rd_overloaded()
  sched/fair: Rename root_domain::overload to ::overloaded
  sched/fair: Use helper functions to access root_domain::overload
  sched/fair: Check root_domain::overload value before update
  sched/fair: Combine EAS check with root_domain::overutilized access
  sched/fair: Simplify the continue_balancing logic in sched_balance_newidle()
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull scheduler updates from Ingo Molnar:

 - Add cpufreq pressure feedback for the scheduler

 - Rework misfit load-balancing wrt affinity restrictions

 - Clean up and simplify the code around ::overutilized and
   ::overload access.

 - Simplify sched_balance_newidle()

 - Bump SCHEDSTAT_VERSION to 16 due to a cleanup of CPU_MAX_IDLE_TYPES
   handling that changed the output.

 - Rework &amp; clean up &lt;asm/vtime.h&gt; interactions wrt arch_vtime_task_switch()

 - Reorganize, clean up and unify most of the higher level
   scheduler balancing function names around the sched_balance_*()
   prefix

 - Simplify the balancing flag code (sched_balance_running)

 - Miscellaneous cleanups &amp; fixes

* tag 'sched-core-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (50 commits)
  sched/pelt: Remove shift of thermal clock
  sched/cpufreq: Rename arch_update_thermal_pressure() =&gt; arch_update_hw_pressure()
  thermal/cpufreq: Remove arch_update_thermal_pressure()
  sched/cpufreq: Take cpufreq feedback into account
  cpufreq: Add a cpufreq pressure feedback for the scheduler
  sched/fair: Fix update of rd-&gt;sg_overutilized
  sched/vtime: Do not include &lt;asm/vtime.h&gt; header
  s390/irq,nmi: Include &lt;asm/vtime.h&gt; header directly
  s390/vtime: Remove unused __ARCH_HAS_VTIME_TASK_SWITCH leftover
  sched/vtime: Get rid of generic vtime_task_switch() implementation
  sched/vtime: Remove confusing arch_vtime_task_switch() declaration
  sched/balancing: Simplify the sg_status bitmask and use separate -&gt;overloaded and -&gt;overutilized flags
  sched/fair: Rename set_rd_overutilized_status() to set_rd_overutilized()
  sched/fair: Rename SG_OVERLOAD to SG_OVERLOADED
  sched/fair: Rename {set|get}_rd_overload() to {set|get}_rd_overloaded()
  sched/fair: Rename root_domain::overload to ::overloaded
  sched/fair: Use helper functions to access root_domain::overload
  sched/fair: Check root_domain::overload value before update
  sched/fair: Combine EAS check with root_domain::overutilized access
  sched/fair: Simplify the continue_balancing logic in sched_balance_newidle()
  ...
</pre>
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</content>
</entry>
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