From: Arnaldo Carvalho de Melo <acme@infradead.org>
To: Hitoshi Mitake <mitake.hitoshi@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>,
linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
h.mitake@gmail.com, kirill.shutemov@linux.intel.com
Subject: Re: [PATCH] perf, tools, bench: Fix memcpy benchmark for large sizes v2
Date: Mon, 22 Jul 2013 13:00:45 -0300 [thread overview]
Message-ID: <20130722160045.GG2157@ghostprotocols.net> (raw)
In-Reply-To: <87ip064k60.wl%mitake.hitoshi@gmail.com>
Em Sat, Jul 20, 2013 at 12:57:27AM +0900, Hitoshi Mitake escreveu:
> At Thu, 18 Jul 2013 15:43:18 -0700, Andi Kleen wrote:
> > glibc calloc() has an optimization to not explicitely memset()
> > very large calloc allocations that just came from mmap(),
> > because they are known to be zero.
> > This could result in the perf memcpy benchmark reading only from
> > the zero page, which gives unrealistic results.
> > Always call memset explicitly on the source area to avoid this problem.
> > +++ b/tools/perf/bench/mem-memcpy.c
> > @@ -115,8 +115,10 @@ static void alloc_mem(void **dst, void **src, size_t length)
> > *src = zalloc(length);
> > - if (!src)
> > + if (!*src)
> In the latest mem-memcpy.c, this if (!src) is already fixed as if
> (!*src). This modification makes applying fail.
I fixed this up, please take a look at:
https://git.kernel.org/cgit/linux/kernel/git/acme/linux.git/commit/?h=perf/core&id=a198996c7afae0097c67a61851f19863e59697b2
https://git.kernel.org/cgit/linux/kernel/git/acme/linux.git/log/?h=perf/core
- Arnaldo
next prev parent reply other threads:[~2013-07-22 16:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-18 22:43 [PATCH] perf, tools, bench: Fix memcpy benchmark for large sizes v2 Andi Kleen
2013-07-19 15:57 ` Hitoshi Mitake
2013-07-19 17:35 ` Andi Kleen
2013-07-22 16:00 ` Arnaldo Carvalho de Melo [this message]
2013-07-22 19:32 ` Andi Kleen
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