linux-kernel - Re: 2.6.36 io bring the system to its knees

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]

Date:	Mon, 1 Nov 2010 01:09:34 +0000 (UTC)
From:	Dimitrios Apostolou <jimis@....net>
To:	linux-kernel@...r.kernel.org
Cc:	linux-mm@...ck.org
Subject: Re: 2.6.36 io bring the system to its knees

Hello, 

On Sun, 31 Oct 2010 09:51:32 +0800, Wu Fengguang wrote:
> It may also help to lower the dirty ratio.
> 
> echo 5 > /proc/sys/vm/dirty_ratio
> 
> Memory pressure + heavy write can easily hurt responsiveness.
> 
> - eats up to 20% (the default value for dirty_ratio) memory with dirty
>   pages and hence increase the memory pressure and number of swap IO

My experience has been different with that. Wouldn't it make more sense 
to _increase_ dirty_ratio (to 50 lets say) and at the same time decrease 
dirty_background_ratio? That way writing to disk starts early, but the 
related apps stall waiting for I/O only when dirty_ratio is reached.


Thanks, 
Dimitris

> 
> - the file copy makes the device write congested and hence makes
>   pageout() easily blocked in get_request_wait()
> 
> As a result every application may be slowed down by the heavy swap IO
> when page fault as well as being blocked when allocating memory (which
> may go into direct reclaim and then call pageout()).
> 
> Thanks,
> Fengguang


--
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/