Re: [PATCH 7/7] sched, x86: Optimize the preempt_schedule()call

From: Jan Beulich
Date: Tue Sep 10 2013 - 09:56:03 EST


>>> On 10.09.13 at 15:42, Ingo Molnar <mingo@xxxxxxxxxx> wrote:

> * Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
>> + .macro SAVE_ALL
>> + pushl_cfi %eax
>> + CFI_REL_OFFSET eax, 0
>> + pushl_cfi %ebp
>> + CFI_REL_OFFSET ebp, 0
>> + pushl_cfi %edi
>> + CFI_REL_OFFSET edi, 0
>> + pushl_cfi %esi
>> + CFI_REL_OFFSET esi, 0
>> + pushl_cfi %edx
>> + CFI_REL_OFFSET edx, 0
>> + pushl_cfi %ecx
>> + CFI_REL_OFFSET ecx, 0
>> + pushl_cfi %ebx
>> + CFI_REL_OFFSET ebx, 0
>> + .endm
>> +
>> + .macro RESTORE_ALL
>> + popl_cfi %ebx
>> + CFI_RESTORE ebx
>> + popl_cfi %ecx
>> + CFI_RESTORE ecx
>> + popl_cfi %edx
>> + CFI_RESTORE edx
>> + popl_cfi %esi
>> + CFI_RESTORE esi
>> + popl_cfi %edi
>> + CFI_RESTORE edi
>> + popl_cfi %ebp
>> + CFI_RESTORE ebp
>> + popl_cfi %eax
>> + CFI_RESTORE eax
>> + .endm
>
> Side note: shouldn't the pushl_cfi and popl_cfi macros be adjusted,
> instead of open coding it?

If you mean the open coding of CFI_REL_OFFSET and CFI_RESTORE,
then no - there may be pushes/pops that don't save the caller's
register values (i.e. where solely the frame pointer adjustment
matters).

If you meant something else, please clarify what.

Jan

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