<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/include/asm-powerpc/paca.h, branch master</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>powerpc: Move include files to arch/powerpc/include/asm</title>
<updated>2008-08-04T02:02:00+00:00</updated>
<author>
<name>Stephen Rothwell</name>
<email>sfr@canb.auug.org.au</email>
</author>
<published>2008-08-01T05:20:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=b8b572e1015f81b4e748417be2629dfe51ab99f9'/>
<id>b8b572e1015f81b4e748417be2629dfe51ab99f9</id>
<content type='text'>
from include/asm-powerpc.  This is the result of a

mkdir arch/powerpc/include/asm
git mv include/asm-powerpc/* arch/powerpc/include/asm

Followed by a few documentation/comment fixups and a couple of places
where &lt;asm-powepc/...&gt; was being used explicitly.  Of the latter only
one was outside the arch code and it is a driver only built for powerpc.

Signed-off-by: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
from include/asm-powerpc.  This is the result of a

mkdir arch/powerpc/include/asm
git mv include/asm-powerpc/* arch/powerpc/include/asm

Followed by a few documentation/comment fixups and a couple of places
where &lt;asm-powepc/...&gt; was being used explicitly.  Of the latter only
one was outside the arch code and it is a driver only built for powerpc.

Signed-off-by: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>[POWERPC] Raise the upper limit of NR_CPUS and move the pacas into the BSS</title>
<updated>2008-04-24T10:58:04+00:00</updated>
<author>
<name>Tony Breeds</name>
<email>tony@bakeyournoodle.com</email>
</author>
<published>2008-04-24T03:43:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=90035fe378c7459ba19c43c63d5f878284224ce4'/>
<id>90035fe378c7459ba19c43c63d5f878284224ce4</id>
<content type='text'>
This adds the required functionality to fill in all pacas at runtime.

With NR_CPUS=1024
text    data     bss     dec     hex filename
 137 1704032       0 1704169  1a00e9 arch/powerpc/kernel/paca.o :Before
 121 1179744  524288 1704153  1a00d9 arch/powerpc/kernel/paca.o :After

Also remove unneeded #includes from arch/powerpc/kernel/paca.c

Signed-off-by: Tony Breeds &lt;tony@bakeyournoodle.com&gt;
Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This adds the required functionality to fill in all pacas at runtime.

With NR_CPUS=1024
text    data     bss     dec     hex filename
 137 1704032       0 1704169  1a00e9 arch/powerpc/kernel/paca.o :Before
 121 1179744  524288 1704153  1a00d9 arch/powerpc/kernel/paca.o :After

Also remove unneeded #includes from arch/powerpc/kernel/paca.c

Signed-off-by: Tony Breeds &lt;tony@bakeyournoodle.com&gt;
Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>[POWERPC] iSeries: Make iseries_reg_save private to iSeries</title>
<updated>2008-04-15T11:21:25+00:00</updated>
<author>
<name>Stephen Rothwell</name>
<email>sfr@canb.auug.org.au</email>
</author>
<published>2008-04-10T06:43:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=30ff2e87ed55e83b4eb436f5f14a7e49ff81ad99'/>
<id>30ff2e87ed55e83b4eb436f5f14a7e49ff81ad99</id>
<content type='text'>
Now that we have the alpaca, the reg_save_ptr is no longer needed in the
paca.  Eradicate all global uses of it and make it static in the iSeries
lpardata.c

Signed-off-by: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Now that we have the alpaca, the reg_save_ptr is no longer needed in the
paca.  Eradicate all global uses of it and make it static in the iSeries
lpardata.c

Signed-off-by: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>taskstats scaled time cleanup</title>
<updated>2008-02-06T18:41:00+00:00</updated>
<author>
<name>Michael Neuling</name>
<email>mikey@neuling.org</email>
</author>
<published>2008-02-06T09:36:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=06b8e878a9bc9301201cffe186eba99c4185f20a'/>
<id>06b8e878a9bc9301201cffe186eba99c4185f20a</id>
<content type='text'>
This moves the ability to scale cputime into generic code.  This allows us
to fix the issue in kernel/timer.c (noticed by Balbir) where we could only
add an unscaled value to the scaled utime/stime.

This adds a cputime_to_scaled function.  As before, the POWERPC version
does the scaling based on the last SPURR/PURR ratio calculated.  The
generic and s390 (only other arch to implement asm/cputime.h) versions are
both NOPs.

Also moves the SPURR and PURR snapshots closer.

Signed-off-by: Michael Neuling &lt;mikey@neuling.org&gt;
Cc: Jay Lan &lt;jlan@engr.sgi.com&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Cc: Heiko Carstens &lt;heiko.carstens@de.ibm.com&gt;
Cc: Martin Schwidefsky &lt;schwidefsky@de.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This moves the ability to scale cputime into generic code.  This allows us
to fix the issue in kernel/timer.c (noticed by Balbir) where we could only
add an unscaled value to the scaled utime/stime.

This adds a cputime_to_scaled function.  As before, the POWERPC version
does the scaling based on the last SPURR/PURR ratio calculated.  The
generic and s390 (only other arch to implement asm/cputime.h) versions are
both NOPs.

Also moves the SPURR and PURR snapshots closer.

Signed-off-by: Michael Neuling &lt;mikey@neuling.org&gt;
Cc: Jay Lan &lt;jlan@engr.sgi.com&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Cc: Heiko Carstens &lt;heiko.carstens@de.ibm.com&gt;
Cc: Martin Schwidefsky &lt;schwidefsky@de.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc: Remove obsolete prototype</title>
<updated>2007-10-19T22:36:33+00:00</updated>
<author>
<name>Julio M. Merino Vidal</name>
<email>jmerino@ac.upc.edu</email>
</author>
<published>2007-10-19T22:36:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=568e0c1119d7ff33fbcddc0dec9e2c799a53352d'/>
<id>568e0c1119d7ff33fbcddc0dec9e2c799a53352d</id>
<content type='text'>
The include/asm-powerpc/paca.h file has a prototype for a function that
does not exist any more; its name is setup_boot_paca.  This function was
removed in commit 4ba99b97dadd35b9ce1438b2bc7c992a4a14a8b1, so its
prototype should have been removed at that time too.

Signed-off-by: Julio M. Merino Vidal &lt;jmerino@ac.upc.edu&gt;
Signed-off-by: Adrian Bunk &lt;bunk@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The include/asm-powerpc/paca.h file has a prototype for a function that
does not exist any more; its name is setup_boot_paca.  This function was
removed in commit 4ba99b97dadd35b9ce1438b2bc7c992a4a14a8b1, so its
prototype should have been removed at that time too.

Signed-off-by: Julio M. Merino Vidal &lt;jmerino@ac.upc.edu&gt;
Signed-off-by: Adrian Bunk &lt;bunk@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>powerpc: add scaled time accounting</title>
<updated>2007-10-18T21:37:28+00:00</updated>
<author>
<name>Michael Neuling</name>
<email>mikey@neuling.org</email>
</author>
<published>2007-10-18T10:06:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=4603ac180a824197c2262747948d0179eb076e9c'/>
<id>4603ac180a824197c2262747948d0179eb076e9c</id>
<content type='text'>
This adds POWERPC specific hooks for scaled time accounting.

POWER6 includes a SPURR register.  The SPURR is based off the PURR register
but is scaled based on CPU frequency and issue rates.  This gives a more
accurate account of the instructions used per task.  The PURR and timebase
will be constant relative to the wall clock, irrespective of the CPU
frequency.

This implementation reads the SPURR register in account_system_vtime which
is only call called on context witch and hard and soft irq entry and exit.
The percentage of user and system time is then estimated using the ratio of
these accounted by the PURR.  If the SPURR is not present, the PURR read.

An earlier implementation of this patch read the SPURR whenever the PURR
was read, which included the system call entry and exit path.
Unfortunately this showed a performance regression on lmbench runs, so was
re-implemented.

I've included the lmbench results here when run bare metal on POWER6.  1st
column is the unpatch results.  2nd column is the results using the below
patch and the 3rd is the % diff of these results from the base.  4th and
5th columns are the results and % differnce from the base using the older
patch (SPURR read in syscall entry/exit path).

                              Base        Scaled-Acct     SPURR-in-syscall
                             Result      Result  % diff    Result % diff
Simple syscall:              0.3086      0.3086  0.0000    0.3452 11.8600
Simple read:                 0.4591      0.4671  1.7425    0.5044 9.86713
Simple write:                0.4364      0.4366  0.0458    0.4731 8.40971
Simple stat:                 2.0055      2.0295  1.1967    2.0669 3.06158
Simple fstat:                0.5962      0.5876  -1.442    0.6368 6.80979
Simple open/close:           3.1283      3.1009  -0.875    3.2088 2.57328
Select on 10 fd's:           0.8554      0.8457  -1.133    0.8667 1.32101
Select on 100 fd's:          3.5292      3.6329  2.9383    3.6664 3.88756
Select on 250 fd's:          7.9097      8.1881  3.5197    8.2242 3.97613
Select on 500 fd's:          15.2659     15.836  3.7357    15.873 3.97814
Select on 10 tcp fd's:       0.9576      0.9416  -1.670    0.9752 1.83792
Select on 100 tcp fd's:      7.248       7.2254  -0.311    7.2685 0.28283
Select on 250 tcp fd's:      17.7742     17.707  -0.375    17.749 -0.1406
Select on 500 tcp fd's:      35.4258     35.25   -0.496    35.286 -0.3929
Signal handler installation: 0.6131      0.6075  -0.913    0.647  5.52927
Signal handler overhead:     2.0919      2.1078  0.7600    2.1831 4.35967
Protection fault:            0.7345      0.7478  1.8107    0.8031 9.33968
Pipe latency:                33.006      16.398  -50.31    33.475 1.42368
AF_UNIX sock stream latency: 14.5093     30.910  113.03    30.715 111.692
Process fork+exit:           219.8       222.8   1.3648    229.37 4.35623
Process fork+execve:         876.14      873.28  -0.32     868.66 -0.8533
Process fork+/bin/sh -c:     2830        2876.5  1.6431    2958   4.52296
File /var/tmp/XXX write bw:  1193497     1195536 0.1708    118657 -0.5799
Pagefaults on /var/tmp/XXX:  3.1272      3.2117  2.7020    3.2521 3.99398

Also, kernel compile times show no difference with this patch applied.

[pbadari@us.ibm.com: Avoid unnecessary PURR reading]
Signed-off-by: Michael Neuling &lt;mikey@neuling.org&gt;
Cc: Balbir Singh &lt;balbir@in.ibm.com&gt;
Cc: Jay Lan &lt;jlan@engr.sgi.com&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Signed-off-by: Badari Pulavarty &lt;pbadari@us.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This adds POWERPC specific hooks for scaled time accounting.

POWER6 includes a SPURR register.  The SPURR is based off the PURR register
but is scaled based on CPU frequency and issue rates.  This gives a more
accurate account of the instructions used per task.  The PURR and timebase
will be constant relative to the wall clock, irrespective of the CPU
frequency.

This implementation reads the SPURR register in account_system_vtime which
is only call called on context witch and hard and soft irq entry and exit.
The percentage of user and system time is then estimated using the ratio of
these accounted by the PURR.  If the SPURR is not present, the PURR read.

An earlier implementation of this patch read the SPURR whenever the PURR
was read, which included the system call entry and exit path.
Unfortunately this showed a performance regression on lmbench runs, so was
re-implemented.

I've included the lmbench results here when run bare metal on POWER6.  1st
column is the unpatch results.  2nd column is the results using the below
patch and the 3rd is the % diff of these results from the base.  4th and
5th columns are the results and % differnce from the base using the older
patch (SPURR read in syscall entry/exit path).

                              Base        Scaled-Acct     SPURR-in-syscall
                             Result      Result  % diff    Result % diff
Simple syscall:              0.3086      0.3086  0.0000    0.3452 11.8600
Simple read:                 0.4591      0.4671  1.7425    0.5044 9.86713
Simple write:                0.4364      0.4366  0.0458    0.4731 8.40971
Simple stat:                 2.0055      2.0295  1.1967    2.0669 3.06158
Simple fstat:                0.5962      0.5876  -1.442    0.6368 6.80979
Simple open/close:           3.1283      3.1009  -0.875    3.2088 2.57328
Select on 10 fd's:           0.8554      0.8457  -1.133    0.8667 1.32101
Select on 100 fd's:          3.5292      3.6329  2.9383    3.6664 3.88756
Select on 250 fd's:          7.9097      8.1881  3.5197    8.2242 3.97613
Select on 500 fd's:          15.2659     15.836  3.7357    15.873 3.97814
Select on 10 tcp fd's:       0.9576      0.9416  -1.670    0.9752 1.83792
Select on 100 tcp fd's:      7.248       7.2254  -0.311    7.2685 0.28283
Select on 250 tcp fd's:      17.7742     17.707  -0.375    17.749 -0.1406
Select on 500 tcp fd's:      35.4258     35.25   -0.496    35.286 -0.3929
Signal handler installation: 0.6131      0.6075  -0.913    0.647  5.52927
Signal handler overhead:     2.0919      2.1078  0.7600    2.1831 4.35967
Protection fault:            0.7345      0.7478  1.8107    0.8031 9.33968
Pipe latency:                33.006      16.398  -50.31    33.475 1.42368
AF_UNIX sock stream latency: 14.5093     30.910  113.03    30.715 111.692
Process fork+exit:           219.8       222.8   1.3648    229.37 4.35623
Process fork+execve:         876.14      873.28  -0.32     868.66 -0.8533
Process fork+/bin/sh -c:     2830        2876.5  1.6431    2958   4.52296
File /var/tmp/XXX write bw:  1193497     1195536 0.1708    118657 -0.5799
Pagefaults on /var/tmp/XXX:  3.1272      3.2117  2.7020    3.2521 3.99398

Also, kernel compile times show no difference with this patch applied.

[pbadari@us.ibm.com: Avoid unnecessary PURR reading]
Signed-off-by: Michael Neuling &lt;mikey@neuling.org&gt;
Cc: Balbir Singh &lt;balbir@in.ibm.com&gt;
Cc: Jay Lan &lt;jlan@engr.sgi.com&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Signed-off-by: Badari Pulavarty &lt;pbadari@us.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>[POWERPC] ppc64: support CONFIG_DEBUG_PREEMPT</title>
<updated>2007-10-03T01:48:44+00:00</updated>
<author>
<name>Hugh Dickins</name>
<email>hugh@veritas.com</email>
</author>
<published>2006-10-31T18:44:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=048c8bc90e53bf1f5feec020a7d482da94894e93'/>
<id>048c8bc90e53bf1f5feec020a7d482da94894e93</id>
<content type='text'>
Add CONFIG_DEBUG_PREEMPT support to ppc64: it was useful for testing
get_paca() preemption.  Cheat a little, just use debug_smp_processor_id()
in the debug version of get_paca(): it contains all the right checks and
reporting, though get_paca() doesn't really use smp_processor_id().

Use local_paca for what might have been called __raw_get_paca().
Silence harmless warnings from io.h and lparcfg.c with local_paca -
it is okay for iseries_lparcfg_data to be referencing shared_proc
with preemption enabled: all cpus should show the same value for
shared_proc.

Why do other architectures need TRACE_IRQFLAGS_SUPPORT for DEBUG_PREEMPT?
I don't know, ppc64 appears to get along fine without it.

Signed-off-by: Hugh Dickins &lt;hugh@veritas.com&gt;
Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add CONFIG_DEBUG_PREEMPT support to ppc64: it was useful for testing
get_paca() preemption.  Cheat a little, just use debug_smp_processor_id()
in the debug version of get_paca(): it contains all the right checks and
reporting, though get_paca() doesn't really use smp_processor_id().

Use local_paca for what might have been called __raw_get_paca().
Silence harmless warnings from io.h and lparcfg.c with local_paca -
it is okay for iseries_lparcfg_data to be referencing shared_proc
with preemption enabled: all cpus should show the same value for
shared_proc.

Why do other architectures need TRACE_IRQFLAGS_SUPPORT for DEBUG_PREEMPT?
I don't know, ppc64 appears to get along fine without it.

Signed-off-by: Hugh Dickins &lt;hugh@veritas.com&gt;
Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>[POWERPC] Introduce address space "slices"</title>
<updated>2007-05-09T06:35:00+00:00</updated>
<author>
<name>Benjamin Herrenschmidt</name>
<email>benh@kernel.crashing.org</email>
</author>
<published>2007-05-08T06:27:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d0f13e3c20b6fb73ccb467bdca97fa7cf5a574cd'/>
<id>d0f13e3c20b6fb73ccb467bdca97fa7cf5a574cd</id>
<content type='text'>
The basic issue is to be able to do what hugetlbfs does but with
different page sizes for some other special filesystems; more
specifically, my need is:

 - Huge pages

 - SPE local store mappings using 64K pages on a 4K base page size
kernel on Cell

 - Some special 4K segments in 64K-page kernels for mapping a dodgy
type of powerpc-specific infiniband hardware that requires 4K MMU
mappings for various reasons I won't explain here.

The main issues are:

 - To maintain/keep track of the page size per "segment" (as we can
only have one page size per segment on powerpc, which are 256MB
divisions of the address space).

 - To make sure special mappings stay within their allotted
"segments" (including MAP_FIXED crap)

 - To make sure everybody else doesn't mmap/brk/grow_stack into a
"segment" that is used for a special mapping

Some of the necessary mechanisms to handle that were present in the
hugetlbfs code, but mostly in ways not suitable for anything else.

The patch relies on some changes to the generic get_unmapped_area()
that just got merged.  It still hijacks hugetlb callbacks here or
there as the generic code hasn't been entirely cleaned up yet but
that shouldn't be a problem.

So what is a slice ?  Well, I re-used the mechanism used formerly by our
hugetlbfs implementation which divides the address space in
"meta-segments" which I called "slices".  The division is done using
256MB slices below 4G, and 1T slices above.  Thus the address space is
divided currently into 16 "low" slices and 16 "high" slices.  (Special
case: high slice 0 is the area between 4G and 1T).

Doing so simplifies significantly the tracking of segments and avoids
having to keep track of all the 256MB segments in the address space.

While I used the "concepts" of hugetlbfs, I mostly re-implemented
everything in a more generic way and "ported" hugetlbfs to it.

Slices can have an associated page size, which is encoded in the mmu
context and used by the SLB miss handler to set the segment sizes.  The
hash code currently doesn't care, it has a specific check for hugepages,
though I might add a mechanism to provide per-slice hash mapping
functions in the future.

The slice code provide a pair of "generic" get_unmapped_area() (bottomup
and topdown) functions that should work with any slice size.  There is
some trickiness here so I would appreciate people to have a look at the
implementation of these and let me know if I got something wrong.

Signed-off-by: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The basic issue is to be able to do what hugetlbfs does but with
different page sizes for some other special filesystems; more
specifically, my need is:

 - Huge pages

 - SPE local store mappings using 64K pages on a 4K base page size
kernel on Cell

 - Some special 4K segments in 64K-page kernels for mapping a dodgy
type of powerpc-specific infiniband hardware that requires 4K MMU
mappings for various reasons I won't explain here.

The main issues are:

 - To maintain/keep track of the page size per "segment" (as we can
only have one page size per segment on powerpc, which are 256MB
divisions of the address space).

 - To make sure special mappings stay within their allotted
"segments" (including MAP_FIXED crap)

 - To make sure everybody else doesn't mmap/brk/grow_stack into a
"segment" that is used for a special mapping

Some of the necessary mechanisms to handle that were present in the
hugetlbfs code, but mostly in ways not suitable for anything else.

The patch relies on some changes to the generic get_unmapped_area()
that just got merged.  It still hijacks hugetlb callbacks here or
there as the generic code hasn't been entirely cleaned up yet but
that shouldn't be a problem.

So what is a slice ?  Well, I re-used the mechanism used formerly by our
hugetlbfs implementation which divides the address space in
"meta-segments" which I called "slices".  The division is done using
256MB slices below 4G, and 1T slices above.  Thus the address space is
divided currently into 16 "low" slices and 16 "high" slices.  (Special
case: high slice 0 is the area between 4G and 1T).

Doing so simplifies significantly the tracking of segments and avoids
having to keep track of all the 256MB segments in the address space.

While I used the "concepts" of hugetlbfs, I mostly re-implemented
everything in a more generic way and "ported" hugetlbfs to it.

Slices can have an associated page size, which is encoded in the mmu
context and used by the SLB miss handler to set the segment sizes.  The
hash code currently doesn't care, it has a specific check for hugepages,
though I might add a mechanism to provide per-slice hash mapping
functions in the future.

The slice code provide a pair of "generic" get_unmapped_area() (bottomup
and topdown) functions that should work with any slice size.  There is
some trickiness here so I would appreciate people to have a look at the
implementation of these and let me know if I got something wrong.

Signed-off-by: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>[POWERPC] Save trap number in bad_stack</title>
<updated>2007-04-24T12:06:59+00:00</updated>
<author>
<name>Olof Johansson</name>
<email>olof@lixom.net</email>
</author>
<published>2007-04-23T15:11:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=687304014f7ca8e2fbb3feaefef356b4a0da65ad'/>
<id>687304014f7ca8e2fbb3feaefef356b4a0da65ad</id>
<content type='text'>
Save the trap number in the case of getting a bad stack in an exception
handler. It is sometimes useful to know what exception it was that caused
this to happen. Without this, no trap number is reported.

Signed-off-by: Olof Johansson &lt;olof@lixom.net&gt;
Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Save the trap number in the case of getting a bad stack in an exception
handler. It is sometimes useful to know what exception it was that caused
this to happen. Without this, no trap number is reported.

Signed-off-by: Olof Johansson &lt;olof@lixom.net&gt;
Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>[POWERPC] Minor paca optimisation</title>
<updated>2007-03-21T11:35:51+00:00</updated>
<author>
<name>Stephen Rothwell</name>
<email>sfr@canb.auug.org.au</email>
</author>
<published>2007-03-16T06:47:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=e91948fd84086020072e022d5463036033d449c1'/>
<id>e91948fd84086020072e022d5463036033d449c1</id>
<content type='text'>
Move the slb_shadow_ptr field into the first cache line since it is
(like everything there) read-only after boot.  It is in fact statically
initialised and thereafter only read.

Signed-off-by: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Acked-by: Michael Neuling &lt;mikey@neuling.org&gt;
Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Move the slb_shadow_ptr field into the first cache line since it is
(like everything there) read-only after boot.  It is in fact statically
initialised and thereafter only read.

Signed-off-by: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Acked-by: Michael Neuling &lt;mikey@neuling.org&gt;
Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
