lkml.org 
[lkml]   [2010]   [Jul]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH] cfq-iosced: Implement IOPS mode and group_idle tunable V3
On Sat, Jul 24, 2010 at 11:07:07AM +0200, Corrado Zoccolo wrote:
> On Sat, Jul 24, 2010 at 10:51 AM, Christoph Hellwig <hch@infradead.org> wrote:
> > To me this sounds like slice_idle=0 is the right default then, as it
> > gives useful behaviour for all systems linux runs on.
> No, it will give bad performance on single disks, possibly worse than
> deadline (deadline at least sorts the requests between different
> queues, while CFQ with slice_idle=0 doesn't even do this for readers).

Not sure if CFQ will be worse than deadline with slice_idle=0. CFQ has
some inbuilt things which should help.

- Readers preempt Writers
- All writers go in one single queue (at one prio level), readers get
their individual queues and can outnumber writers.

So I guess CFQ with slice_idle=0 should not be worse than deadline in terms
of read latencies.

Vivek


\
 
 \ /
  Last update: 2010-07-26 16:35    [W:0.948 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site