Signed-off-by: Paul Mundt <lethal@linux-sh.org>
A number of small optimisations to FPU handling, in particular: - move the task USEDFPU flag from the thread_info flags field (which is accessed asynchronously to the thread) to a new status field, which is only accessed by the thread itself. This allows locking to be removed in most cases, or can be reduced to a preempt_lock(). This mimics the i386 behaviour. - move the modification of regs->sr and thread_info->status flags out of save_fpu() to __unlazy_fpu(). This gives the compiler a better chance to optimise things, as well as making save_fpu() symmetrical with restore_fpu() and init_fpu(). - implement prepare_to_copy(), so that when creating a thread, we can unlazy the FPU prior to copying the thread data structures. Also make sure that the FPU is disabled while in the kernel, in particular while booting, and for newly created kernel threads, In a very artificial benchmark, the execution time for 2500000 context switches was reduced from 50 to 45 seconds. Signed-off-by: Stuart Menefy <stuart.menefy@st.com> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
sh port of the sLeAZY-fpu feature currently implemented for some architectures such us i386. Right now the SH kernel has a 100% lazy fpu behaviour. This is of course great for applications that have very sporadic or no FPU use. However for very frequent FPU users... you take an extra trap every context switch. The patch below adds a simple heuristic to this code: after 5 consecutive context switches of FPU use, the lazy behavior is disabled and the context gets restored every context switch. After 256 switches, this is reset and the 100% lazy behavior is returned. Tests with LMbench showed no regression. I saw a little improvement due to the prefetching (~2%). The tests below also show that, with this sLeazy patch, indeed, the number of FPU exceptions is reduced. To test this. I hacked the lat_ctx LMBench to use the FPU a little more. sLeasy implementation =========================================== switch_to calls | 79326 sleasy calls | 42577 do_fpu_state_restore calls| 59232 restore_fpu calls | 59032 Exceptions: 0x800 (FPU disabled ): 16604 100% Leazy (default implementation) =========================================== switch_to calls | 79690 do_fpu_state_restore calls | 53299 restore_fpu calls | 53101 Exceptions: 0x800 (FPU disabled ): 53273 Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com> Signed-off-by: Stuart Menefy <stuart.menefy@st.com> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Many of these symbols went away completely, or we just never cared about them in the first place. Trim the exports down to the essential set. Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This patches will trigger a reboot using the watchdog timer instead of double fault. Unlike the previous method, this one actually works in 32 bit mode. Reset should also be cleaner. Signed-off-by: Jon Frosdick <jon.frosdick@st.com> Signed-off-by: Carl Shaw <carl.shaw@st.com> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Annotate __switch_to() so that the function graph tracer does not try to
trace it. Use __notrace_funcgraph, as opposed to notrace, so that other
tracers can continue to trace __switch_to().
The reason that we don't want to trace __switch_to() with the function
graph tracer is because of how the return address stack in task_struct
is implemented. When we enter __switch_to we store the real return
address on prev's ret_stack. When we return from __switch_to() we've
patched the return address on the kernel stack to be
return_to_handler. Calling return_to_handler we do,
-> ftrace_return_to_handler()
-> ftrace_pop_return_ftrace()
Which tries to pop the real return address from current->ret_stack. The
problem being that we stored the return address on prev->ret_stack, but
current now points to next, and next->ret_stack doesn't contain the
correct return address (and is possibly even empty).
Signed-off-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6: (56 commits) sh: Fix declaration of __kernel_sigreturn and __kernel_rt_sigreturn sh: Enable soc-camera in ap325rxa/migor/se7724 defconfigs. sh: remove stray markers. sh: defconfig updates. sh: pci: Initial PCI-Express support for SH7786 Urquell board. sh: Generic HAVE_PERF_COUNTER support. SH: convert migor to soc-camera as platform-device SH: convert ap325rxa to soc-camera as platform-device soc-camera: unify i2c camera device platform data sh: add platform data for r8a66597-hcd in setup-sh7723 sh: add platform data for r8a66597-hcd in setup-sh7366 sh: x3proto: add platform data for r8a66597-hcd sh: highlander: add platform data for r8a66597-hcd sh: sh7785lcr: add platform data for r8a66597-hcd sh: turn off irqs when disabling CMT/TMU timers sh: use kzalloc() for cpg clocks sh: unbreak WARN_ON() sh: Use generic atomic64_t implementation. sh: Revised clock function in highlander sh: Update r7780mp defconfig ...
avr32, mn10300, parisc, s390, sh, xtensa: They never set PT_DTRACE, but clear it after do_execve(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: David Howells <dhowells@redhat.com> Acked-by: Kyle McMartin <kyle@mcmartin.ca> Cc: Grant Grundler <grundler@parisc-linux.org> Cc: Matthew Wilcox <matthew@wil.cx> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Acked-by: Paul Mundt <lethal@linux-sh.org> Acked-by: Chris Zankel <chris@zankel.net> Acked-by: Roland McGrath <roland@redhat.com> Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
arch/sh has a couple of stray markers without any users introduced in commit 3d58695edbfac785161bf282dc11fd42a483d6c9. Remove them in preparation of removing the markers in favour of the TRACE_EVENT macro (and also because we don't keep dead code around). Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Paul Mundt <lethal@linux-sh.org>