Messages in this thread | | | Date | Tue, 24 Jan 2023 09:06:08 -0700 | Subject | Re: [PATCH] x86/fpu: don't set TIF_NEED_FPU_LOAD for PF_IO_WORKER threads | From | Jens Axboe <> |
| |
On 1/24/23 8:40 AM, Peter Zijlstra wrote: > On Tue, Jan 24, 2023 at 08:23:20AM -0700, Jens Axboe wrote: >> We don't set it on PF_KTHREAD threads as they never return to userspace, >> and PF_IO_WORKER threads are identical in that regard. As they keep >> running in the kernel until they die, skip setting the FPU flag on them. > > No objection to the actual patch; but this changelog fails to tell us > why this is important. > > What made you get up and write this patch :-) Presumably this is a > performance issue? If so, can you quantify how much?
You snipped the part where that was explained, but arguably that should probably go into the commit message itself:
"Not urgent, more of a cosmetic thing that was found while debugging and issue and pondering why the FPU flag is set on these threads."
So it's not really a performance issue, it was just something odd that got me scratching my head when debugging another issue and poking at the flags.
Want a resend of it, or will you just augment the commit message?
-- Jens Axboe
| |