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:	Fri, 15 Jan 2010 21:24:23 +0100
From:	Corrado Zoccolo <czoccolo@...il.com>
To:	Jeff Moyer <jmoyer@...hat.com>
Cc:	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>,
	Shaohua Li <shaohua.li@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"jens.axboe@...cle.com" <jens.axboe@...cle.com>,
	"Zhang, Yanmin" <yanmin.zhang@...el.com>
Subject: Re: [PATCH]cfq-iosched: don't take requests with long distence as 
	close

On Fri, Jan 15, 2010 at 8:45 PM, Jeff Moyer <jmoyer@...hat.com> wrote:
> Corrado Zoccolo <czoccolo@...il.com> writes:
>
>> Hi Jeff,
>> I think this patch has the same flaw as Shaohua's.
>> The seekiness check that you introduce in cfq_rq_close is already
>> present in its caller, cfq_close_cooperator, so it is not effective.
>
> I don't think so.  There are two queues, here.  One queue is checked by
> the caller, and that is the cur_cfqq.  The __cfqq needs to also be
> checked.
The other one, i.e. the returned one, is also checked by the caller,
some lines below.
1756         cfqq = cfqq_close(cfqd, cur_cfqq);
1757         if (!cfqq)
1758                 return NULL;
1759
1760         /* If new queue belongs to different cfq_group, don't choose it */
1761         if (cur_cfqq->cfqg != cfqq->cfqg)
1762                 return NULL;
1763
1764         /*
1765          * It only makes sense to merge sync queues.
1766          */
1767         if (!cfq_cfqq_sync(cfqq))
1768                 return NULL;
1769         if (CFQQ_SEEKY(cfqq))
1770                 return NULL;
>
>> Up to now, the only patch that improves this situation is the one that
>> changes the unmerge policy to unmerge after a single time slice.
>
> Yes, I definitely agree with that, and I think that patch should go in.
>
> Cheers,
> Jeff
>



-- 
__________________________________________________________________________

dott. Corrado Zoccolo                          mailto:czoccolo@...il.com
PhD - Department of Computer Science - University of Pisa, Italy
--------------------------------------------------------------------------
The self-confidence of a warrior is not the self-confidence of the average
man. The average man seeks certainty in the eyes of the onlooker and calls
that self-confidence. The warrior seeks impeccability in his own eyes and
calls that humbleness.
                               Tales of Power - C. Castaneda
--
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/

Powered by blists - more mailing lists