lkml.org 
[lkml]   [2018]   [Jan]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] x86: Align TLB invalidation info
From
Date
Dave Hansen <dave.hansen@linux.intel.com> wrote:

> On 01/31/2018 12:48 PM, Nadav Amit wrote:
>>>> On Jan 31, 2018, at 12:11 PM, Nadav Amit <namit@vmware.com> wrote:
>>>>
>>>> The TLB invalidation info is allocated on the stack, which might cause
>>>> it to be unaligned. Since this information may be transferred to
>>>> different cores for TLB shootdown, this might result in an additional
>>>> cache-line bouncing between the cores.
>>>>
>>>> GCC provides a way to deal with it by using
>>>> __builtin_alloca_with_align(). Use it to avoid the bouncing cache lines.
>>> Eww. How about __aligned?
>> Err.. Stupid me. For some reason I remembered I tried it and it didn’t have
>> the desired effect, which caused me to assume it does not work for variables
>> on the stack. Anyhow, it does the work. I’ll submit v2.
>
> Also, just curious, but did you find this situation by inspection or did
> it show up in a profile somewhere?

Actually, not. I considered adding data to info for a different reason
(which eventually I deserted); I was assuming you will all kill me for
increasing the size, so this was a preemption step.

\
 
 \ /
  Last update: 2018-01-31 21:52    [W:0.037 / U:0.012 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site