[haiku-commits] Re: BRANCH pdziepak-github.memcpy-v2 [c4c0758] src/system/kernel/arch/x86/64 src/system/libroot/posix/string/arch/x86_64 src/system/kernel/arch/x86 headers/private/kernel/arch/x86/64
- From: Paweł Dziepak <pdziepak@xxxxxxxxxxx>
- To: haiku-commits@xxxxxxxxxxxxx
- Date: Wed, 10 Sep 2014 22:36:14 +0200
2014-09-10 22:31 GMT+02:00 pdziepak-github.memcpy-v2 <community@xxxxxxxxxxxx
>:
> added 2 changesets to branch 'refs/remotes/pdziepak-github/memcpy-v2'
> old head: bb159c73fb99410fb591ee25b1fe0b92cd5870a5
> new head: c4c07587ea65bf0a7854ca91204324301b72e8df
> overview: https://github.com/pdziepak/Haiku/compare/bb159c7...c4c0758
>
>
> ----------------------------------------------------------------------------
>
> f4c3362: kernel/x86_64: save fpu state at interrupts
>
> The kernel is allowed to use fpu anywhere so we must make sure that
> user state is not clobbered by saving fpu state at interrupt entry.
> There is no need to do that in case of system calls since all fpu
> data registers are caller saved.
>
> We do not need, though, to save the whole fpu state at task swich
> (again, thanks to calling convention). Only status and control
> registers are preserved. This patch actually adds xmm0-15 register
> to clobber list of task swich code, but the only reason of that is
> to make sure that nothing bad happens inside the function that
> executes that task swich. Inspection of the generated code shows
> that no xmm registers are actually saved.
>
I admit, this is mess. Definitely, the next thing I am going to do for
Haiku is rewriting kernel entry/exit code.
> Signed-off-by: Paweł Dziepak <pdziepak@xxxxxxxxxxx>
>
> c4c0758: libroot/x86_64: new memcpy implementation
>
> This patch introduces new memcpy() implementation that improves the
> performance when the buffer is small. It was written for processors that
> support ERMSB, but performs reasonably well on older CPUs as well.
>
> The following benchmarks were done on Haswell i7 running Debian Jessie
> with Linux 3.16.1. In each iteration 64MB buffer was copied, the
> parameter "size" is the size of the buffer passed in a single call (i.e.
> for "size: 2" memcpy() was called ~32 million times to copy the whole
> 64MB).
>
> f - original implementation, g - new implementation, all buffers 16 byte
> aligned
>
> cpy, size: 8, f: 79971 µs, g: 20419 µs, ∆: 74.47%
> cpy, size: 32, f: 42068 µs, g: 12159 µs, ∆: 71.10%
> cpy, size: 128, f: 13408 µs, g: 10359 µs, ∆: 22.74%
> cpy, size: 512, f: 10634 µs, g: 10433 µs, ∆: 1.89%
> cpy, size: 1024, f: 10474 µs, g: 10536 µs, ∆: -0.59%
> cpy, size: 4096, f: 9419 µs, g: 8630 µs, ∆: 8.38%
>
> f - glibc 2.19 implementation, g - new implementation, all buffers 16
> byte
> aligned
>
> cpy, size: 8, f: 26299 µs, g: 20919 µs, ∆: 20.46%
> cpy, size: 32, f: 11146 µs, g: 12159 µs, ∆: -9.09%
> cpy, size: 128, f: 10778 µs, g: 10354 µs, ∆: 3.93%
> cpy, size: 512, f: 12291 µs, g: 10426 µs, ∆: 15.17%
> cpy, size: 1024, f: 13923 µs, g: 10571 µs, ∆: 24.08%
> cpy, size: 4096, f: 11770 µs, g: 8671 µs, ∆: 26.33%
>
> f - glibc 2.19 implementation, g - new implementation, all buffers
> unaligned
>
> cpy, size: 16, f: 13376 µs, g: 13009 µs, ∆: 2.74%
> cpy, size: 32, f: 11130 µs, g: 12171 µs, ∆: -9.35%
> cpy, size: 64, f: 11017 µs, g: 11231 µs, ∆: -1.94%
> cpy, size: 128, f: 10884 µs, g: 10407 µs, ∆: 4.38%
> cpy, size: 256, f: 10826 µs, g: 10106 µs, ∆: 6.65%
> cpy, size: 512, f: 12354 µs, g: 10396 µs, ∆: 15.85%
>
If anyone is interested this is the code used for measurements (both memcpy
and memset): https://gist.github.com/pdziepak/2ae4e5ea88e8477d136a
Signed-off-by: Paweł Dziepak <pdziepak@xxxxxxxxxxx>
>
> [ Paweł Dziepak <pdziepak@xxxxxxxxxxx>
> ]
>
>
> ----------------------------------------------------------------------------
>
> 11 files changed, 244 insertions(+), 67 deletions(-)
> headers/private/kernel/arch/x86/64/cpu.h | 10 +-
> headers/private/kernel/arch/x86/64/iframe.h | 1 +
> headers/private/kernel/arch/x86/arch_cpu.h | 11 +-
> src/system/kernel/arch/x86/64/arch.S | 29 -----
> src/system/kernel/arch/x86/64/interrupts.S | 67 ++++++++--
> src/system/kernel/arch/x86/64/thread.cpp | 31 ++---
> src/system/kernel/arch/x86/arch_cpu.cpp | 5 +-
> src/system/kernel/arch/x86/arch_thread.cpp | 4 +
> .../kernel/arch/x86/arch_user_debugger.cpp | 23 +++-
> src/system/kernel/arch/x86/asm_offsets.cpp | 1 +
> .../posix/string/arch/x86_64/arch_string.cpp | 129 ++++++++++++++++++-
>
<snip, full diff>
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