linux-kernel - Re: [PATCH v3 0/5] Rework mtime and ctime updates on mmaped writes

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:	Wed, 4 Sep 2013 10:33:22 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Jan Kara <jack@...e.cz>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
	Dave Chinner <david@...morbit.com>,
	"Theodore Ts'o" <tytso@....edu>,
	Dave Hansen <dave.hansen@...ux.intel.com>, xfs@....sgi.com,
	Tim Chen <tim.c.chen@...ux.intel.com>,
	Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH v3 0/5] Rework mtime and ctime updates on mmaped writes

On Wed, Sep 4, 2013 at 8:08 AM, Jan Kara <jack@...e.cz> wrote:
> On Thu 22-08-13 17:03:16, Andy Lutomirski wrote:
>> Writes via mmap currently update mtime and ctime in ->page_mkwrite.
>> This hurts both throughput and latency.  In workloads that dirty a
>> large number of mmapped pages, ->page_mkwrite can be hot and
>> file_update_time is slow and scales poorly.  Updating timestamps can
>> also sleep, which hurts latency for real-time workloads.
>   It would help to make your case if you posted the latency comparison
> before & after the patchset in this introductory email. We can then see
> how significant is the reduction of latency...

Will do, although the data from my workload will be a little strange.

I was hoping that Dave Hansen would re-run his benchmark with these
patches applied.  I tried to run it, but it wasn't obvious what the
numbers that spewed out meant.

--Andy

>
>                                                                 Honza
> --
> Jan Kara <jack@...e.cz>
> SUSE Labs, CR



-- 
Andy Lutomirski
AMA Capital Management, LLC
--
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/