linux-kernel - Re: [PATCH] memory hotplug: Speed up add/remove when blocks are larger than PAGES_PER

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: <20110511151900.GA19603@suse.de>
Date:	Wed, 11 May 2011 08:19:00 -0700
From:	Greg KH <gregkh@...e.de>
To:	Anton Blanchard <anton@...ba.org>
Cc:	nfont@...tin.ibm.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] memory hotplug: Speed up add/remove when blocks are
 larger than PAGES_PER_SECTION

On Wed, May 11, 2011 at 05:25:14PM +1000, Anton Blanchard wrote:
> 
> On ppc64 the minimum memory section for hotplug is 16MB but most
> recent machines have a memory block size of 256MB. This means
> memory_block_change_state does 16 separate calls to
> memory_section_action.
> 
> This also means we call the notifiers 16 times and the hook
> in the ehea network driver is quite costly. To offline one 256MB
> region takes:
> 
> # time echo offline > /sys/devices/system/memory/memory32/state
> 7.9s
> 
> This patch removes the loop and calls online_pages or
> remove_memory once for the entire region and in doing so makes
> the logic simpler since we don't have to back out if things fail
> part way through.
> 
> The same test to offline one region now takes:
> 
> # time echo online > /sys/devices/system/memory/memory32/state
> 0.67s
> 
> Over 11 times faster.

Very nice job, I'll queue this up for .40.

thanks,

greg k-h
--
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/