[lkml]   [2006]   [Jun]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] readahead: initial method - expected read size - fix fastcall
On Tue, 6 Jun 2006 10:26:06 +0800 Fengguang Wu wrote:
> On Mon, Jun 05, 2006 at 03:17:20AM +0200, Voluspa wrote:
> > Patch:
> >
> It seems that the patch has some problem:
> The above statements was displaced, rendering the if() clause to fail all the time.
> That defeats the small file optimization, for ra_thrash_bytes will remain small.

Which rendered all my testing invalid. Nice... It came about with the
update-01to04of04 and must have elicited a "fuzz" that I neglected to

Sorry to have caused you grief and extra work, Wu. I can only point
towards the _Caveat and preemptive Mea Culpa_.

> Voluspa, I attached an updated patch, including two more performance tunings.
> Please take it when you find time to do more benchmarks, thanks.
> I'd suggest that you(and other kind people interested in testing it out) to run
> blockdev --setra 2048 /dev/[sda/sda1/...]
> before each benchmark to ensure fairness and simplicity of analysis, thanks.

I'm in the process of writing up a new report after having tested for ca 6
hours straight (repenting mood). Will post in the original thread:

Adaptive Readahead V14 - statistics question...

The subject has a 'higher profile' than this one and might pull in future

Note to Andrew; Revised Conclusion: On _this_ machine, with _these_ operations,
Adaptive Readahead in its current incarnation and default settings is a slight
_loss_. However, if the readahead size is lowered from 2048 to 256, it becomes
a slight _gain_ or at least stays in parity with normal readahead.

Mats Johannesson
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2006-06-08 09:34    [W:0.089 / U:0.212 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site