From: Borislav Petkov <bp@alien8.de>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>,
Dan Williams <dan.j.williams@intel.com>,
elliott@hpe.com, Brian Gerst <brgerst@gmail.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-nvdimm@ml01.01.org, x86@kernel.org
Subject: Re: [PATCH v10 3/4] x86, mce: Add __mcsafe_copy()
Date: Wed, 10 Feb 2016 21:50:35 +0100 [thread overview]
Message-ID: <20160210205035.GB11832@pd.tnic> (raw)
In-Reply-To: <20160210193905.GB29493@agluck-desk.sc.intel.com>
On Wed, Feb 10, 2016 at 11:39:05AM -0800, Luck, Tony wrote:
> On Wed, Feb 10, 2016 at 11:58:43AM +0100, Borislav Petkov wrote:
> > But one could take out that function do some microbenchmarking with
> > different sizes and once with the current version and once with the
> > pushes and pops of r1[2-5] to see where the breakeven is.
>
> On a 4K page copy from a source address that isn't in the
> cache I see all sorts of answers.
>
> On my desktop (i7-3960X) it is ~50 cycles slower to push and pop the four
> registers.
>
> On my latest Xeon - I can't post benchmarks ... but also a bit slower.
>
> On an older Xeon it is a few cycles faster (but even though I'm
> looking at the median of 10,000 runs I see more run-to-run variation
> that I see difference between register choices.
Hmm, strange. Can you check whether perf doesn't show any significant
differences too. Something like:
perf stat --repeat 100 --sync --pre 'echo 3 > /proc/sys/vm/drop_caches' -- ./mcsafe_copy_1
and then
perf stat --repeat 100 --sync --pre 'echo 3 > /proc/sys/vm/drop_caches' -- ./mcsafe_copy_2
That'll be interesting...
Thanks.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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next prev parent reply other threads:[~2016-02-10 20:50 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-04 20:36 [PATCH v10 0/4] Machine check recovery when kernel accesses poison Tony Luck
2015-12-31 19:40 ` [PATCH v10 2/4] x86, mce: Check for faults tagged in EXTABLE_CLASS_FAULT exception table entries Tony Luck
2016-01-08 20:49 ` [PATCH v10 1/4] x86: Expand exception table to allow new handling options Tony Luck
2016-01-08 21:18 ` [PATCH v10 3/4] x86, mce: Add __mcsafe_copy() Tony Luck
2016-02-07 16:49 ` Borislav Petkov
2016-02-09 23:15 ` Luck, Tony
2016-02-10 10:58 ` Borislav Petkov
2016-02-10 19:39 ` Luck, Tony
2016-02-10 20:50 ` Borislav Petkov [this message]
2016-02-07 16:55 ` Borislav Petkov
2016-02-07 20:54 ` Richard Weinberger
2016-01-30 0:00 ` [PATCH v10 4/4] x86: Create a new synthetic cpu capability for machine check recovery Tony Luck
2016-02-07 17:10 ` Borislav Petkov
2016-02-09 23:38 ` Luck, Tony
2016-02-10 11:06 ` Borislav Petkov
2016-02-10 19:27 ` Luck, Tony
2016-02-11 11:55 ` Borislav Petkov
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