lkml.org 
[lkml]   [2015]   [Jun]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH 00/12] x86/mm: Implement lockless pgd_alloc()/pgd_free()

[ I fat-fingered the linux-mm Cc:, so every reply will bounce on that,
sorry about that :-/ Fixed it in this mail's Cc: list. ]

* Ingo Molnar <mingo@kernel.org> wrote:

> Waiman Long reported 'pgd_lock' contention on high CPU count systems and
> proposed moving pgd_lock on a separate cacheline to eliminate false sharing and
> to reduce some of the lock bouncing overhead.

So 'pgd_lock' is a global lock, used for every new task creation:

arch/x86/mm/fault.c:DEFINE_SPINLOCK(pgd_lock);

which with a sufficiently high CPU count starts to hurt.

Thanks,

Ingo


\
 
 \ /
  Last update: 2015-06-11 16:41    [W:0.175 / U:25.216 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site