linux-kernel - Re: [ext3][kernels >= 2.6.20.7 at least] KDE going comatose when FS is under heavy write load (massive starvation)

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: <Pine.LNX.4.64.0704281909320.14529@artax.karlin.mff.cuni.cz>
Date:	Sat, 28 Apr 2007 19:11:37 +0200 (CEST)
From:	Mikulas Patocka <mikulas@...ax.karlin.mff.cuni.cz>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Mike Galbraith <efault@....de>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jens Axboe <jens.axboe@...cle.com>
Subject: Re: [ext3][kernels >= 2.6.20.7 at least] KDE going comatose when FS
 is under heavy write load (massive starvation)

> So perhaps if there's any privileged reads going on then we should limit
> writes to a depth of 2 at most, with some timeout mechanism that would

SCSI has a "high priority" bit in the command block, so you can just set 
it --- but I am not sure how well do disks support it.

Mikulas

> gradually allow the deepening of the hardware queue, as long as no
> highprio reads come inbetween? With 2 pending requests and even assuming
> worst-case seeks the user-visible latency would be on the order of 20-30
> msecs, which is at the edge of human perception. The problem comes when
> a hardware queue of 32-64 entries starves that one highprio read which
> then results in a 2+ seconds latency.
>
> 	Ingo
>
-
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/