From: "Ma, Ling" <ling.ma@intel.com>
To: Konrad Rzeszutek Wilk <konrad@kernel.org>
Cc: "mingo@elte.hu" <mingo@elte.hu>, "hpa@zytor.com" <hpa@zytor.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH RFC 2/2] [x86] Optimize copy_page by re-arranging instruction sequence and saving register
Date: Fri, 12 Oct 2012 03:37:50 +0000 [thread overview]
Message-ID: <B2310DA9850C8743AA7AA0055500E90F0FD709F9@SHSMSX102.ccr.corp.intel.com> (raw)
In-Reply-To: <20121011143527.GA2408@localhost.localdomain>
> > Load and write operation occupy about 35% and 10% respectively for
> > most industry benchmarks. Fetched 16-aligned bytes code include about
> > 4 instructions, implying 1.34(0.35 * 4) load, 0.4 write.
> > Modern CPU support 2 load and 1 write per cycle, so throughput from
> > write is bottleneck for memcpy or copy_page, and some slight CPU only
> > support one mem operation per cycle. So it is enough to issue one
> read
> > and write instruction per cycle, and we can save registers.
>
> So is that also true for AMD CPUs?
Although Bulldozer put 32byte instruction into decoupled 16byte entry buffers,
it still decode 4 instructions per cycle, so 4 instructions will be fed into execution unit and
2 loads ,1 write will be issued per cycle.
Thanks
Ling
next prev parent reply other threads:[~2012-10-12 3:37 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-11 12:29 [PATCH RFC 2/2] [x86] Optimize copy_page by re-arranging instruction sequence and saving register ling.ma
2012-10-11 13:40 ` Andi Kleen
2012-10-12 3:10 ` Ma, Ling
2012-10-12 13:35 ` Andi Kleen
2012-10-12 14:54 ` Ma, Ling
2012-10-12 15:14 ` Andi Kleen
2012-10-11 14:35 ` Konrad Rzeszutek Wilk
2012-10-12 3:37 ` Ma, Ling [this message]
2012-10-12 6:18 ` Borislav Petkov
2012-10-12 9:07 ` Ma, Ling
2012-10-12 18:04 ` Borislav Petkov
2012-10-14 10:58 ` Borislav Petkov
2012-10-15 5:00 ` Ma, Ling
2012-10-15 5:13 ` George Spelvin
2012-10-12 21:02 George Spelvin
2012-10-12 23:17 ` Borislav Petkov
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