linux-kernel - [PATCH 0 of 9] x86/smp function calls: convert x86 tlb flushes to use function calls [POST 2]

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-next>] [day] [month] [year] [list]

Message-Id: <patchbomb.1219083817@localhost>
Date:	Mon, 18 Aug 2008 11:23:37 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
	Andi Kleen <andi@...stfloor.org>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	Jens Axboe <jens.axboe@...cle.com>
Subject: [PATCH 0 of 9] x86/smp function calls: convert x86 tlb flushes to use
	function calls [POST 2]

This series:
 - adds a simple debugfs profiling entry for cross-cpu tlb flushes
 - converts them to using smp_call_function_mask
 - unifies 32 and 64-bit tlb flushes
 - converts smp_call_function to using multiple queues (using the now
   freed vectors)
 - allows config-time adjustment of the number of queues
 - adds a kernel parameter to disable multi-queue in case it causes
   problems

The main concern is whether using smp_call_function adds an
unacceptible performance hit to cross-cpu tlb flushes.  My limited
measurements show a ~35% regression in latency for a particular flush;
it would be interesting to try this on a wider range of hardware.  I
gather the effect tlb flush performance is very application specific
as well, but I'm not sure what benchmarks show what effects.

Trading off agains the latency of a given flush, the smp_function_call
mechanism allows multiple requests to be queued, and so may improve
throughput on a system-wide basis.

So, I'd like people to try this out and see what performance effects it
has.

Thanks,
	J

--
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/