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

[Andy Lutomirski <luto@xxxxxxxxxxxxxx>]

On Wed, Sep 4, 2013 at 8:08 AM, Jan Kara <jack@xxxxxxx> 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@xxxxxxx>
> SUSE Labs, CR



-- 
Andy Lutomirski
AMA Capital Management, LLC