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Re: [PATCH 1/2] Single thread optimization for malloc atomics
- From: Rich Felker <dalias at libc dot org>
- To: OndÅej BÃlka <neleai at seznam dot cz>
- Cc: Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>, "GNU C. Library" <libc-alpha at sourceware dot org>
- Date: Wed, 30 Apr 2014 12:06:18 -0400
- Subject: Re: [PATCH 1/2] Single thread optimization for malloc atomics
- Authentication-results: sourceware.org; auth=none
- References: <53610133 dot 3070908 at linux dot vnet dot ibm dot com> <20140430141845 dot GA6882 at domone dot podge>
On Wed, Apr 30, 2014 at 04:18:45PM +0200, OndÅej BÃlka wrote:
> On Wed, Apr 30, 2014 at 10:57:07AM -0300, Adhemerval Zanella wrote:
> > This patch adds a single-thread optimization for malloc atomic usage to
> > first check if process is single-thread (ST) and if so use normal
> > load/store instead of atomic instructions.
> >
> How fast is tls on power? When we add a per-thread cache as I suggested
> then it would have most of time same performance as singlethread, with
> overhead one tls variable access per malloc call.
Extremely fast: the TLS address is simply kept in a general-purpose
register.
Rich