lkml.org 
[lkml]   [1999]   [Jul]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: clustering page-ins
On Tue, 27 Jul 1999, Jamie Lokier wrote:
> If the sweep is relatively fast you want either (a) large clusters or
> (b) to trigger read-ahead _several clusters_ ahead. Specifically, the
> trigger point has to be N pages ahead, where N is going to imply large
> clusters or many smaller clusters. Very large clusters are bad
> because they use a lot of memory, and the large requests hog the I/O
> subsystem.
>
> If the sweep is relatively slow, for minimal read-ahead page usage,
> trigger read-ahead near the end of the previously read segment.
> However the segments will be quite small in this case, so triggering
> at the beginning of the previously read segment (Steven's suggestion)
> seems fine.

all the read-ahead and clustering parameters are adustable, but how do you
propose to measure the sweep rate? how can we tell when a cluster becomes
very large, and thus is affecting other I/O bound jobs?

- Chuck Lever
--
corporate: <chuckl@netscape.com>
personal: <chucklever@netscape.net> or <cel@monkey.org>

The Linux Scalability project:
http://www.citi.umich.edu/projects/linux-scalability/



-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:53    [W:3.420 / U:0.112 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site