linux-kernel - Re: [PATCH] x86: Run checksumming in parallel accross multiple alu's

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1381883650.2045.92.camel@edumazet-glaptop.roam.corp.google.com>
Date:	Tue, 15 Oct 2013 17:34:10 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Joe Perches <joe@...ches.com>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Neil Horman <nhorman@...driver.com>,
	linux-kernel@...r.kernel.org, sebastien.dugue@...l.net,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Subject: Re: [PATCH] x86: Run checksumming in parallel accross multiple alu's

On Tue, 2013-10-15 at 09:21 -0700, Joe Perches wrote:

> Ingo, Eric _showed_ that the prefetch is good here.
> How about looking at a little optimization to the minimal
> prefetch that gives that level of performance.

Wait a minute, my point was to remind that main cost is the
memory fetching.

Its nice to optimize cpu cycles if we are short of them,
but in the csum_partial() case, the bottleneck is the memory.

Also I was wondering on the implications of changing reads order,
as it might fool cpu predictions.

I do not particularly care about finding the right prefetch stride,
I think Intel guys know better than me.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/