lkml.org 
[lkml]   [2015]   [Oct]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC] perf: fix building for ARCv1
On Mon, Oct 19, 2015 at 09:46:35AM +0000, Vineet Gupta wrote:
> On ARC we could use the atomic EXchange to implement a user space only binary
> semaphore - these atomic ops will be small duration so it is OK to spin wait for a
> little bit. That's how the old pthread library worked for ARC w/o any atomic support.

That has the obvious problem of lock-holder-preemption and the horrible
performance issues that result from that.

I think the syscall at least has deterministic behaviour, whereas that
userspace spin loop has this abysmal worst case thing.


\
 
 \ /
  Last update: 2015-10-19 12:21    [W:0.208 / U:0.648 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site