[lkml]   [2003]   [Feb]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: stochastic fair queueing in the elevator [Re: [BENCHMARK] 2.4.20-ck3 / aa / rmap with contest]
Andrew Morton wrote:

>Andrea Arcangeli <> wrote:
>>It's the readahead in my tree that allows the reads to use the max scsi
>>command size. It has nothing to do with the max scsi command size
>Oh bah.
>- *max_ra++ = vm_max_readahead;
>+ *max_ra = ((128*4) >> (PAGE_SHIFT - 10)) - 1;
>Well of course that will get bigger bonnie numbers, for exactly the reasons
>I've explained. It will seek between files after every 512k rather than
>after every 128k.
Though Andrea did say it is a "single threaded" streaming read.
That is what I can't understand. Movement of the disk head should
be exactly the same in either situation and 128K is not exactly
a pitiful request size - so it suggests a quirk somewhere. It
is not as if the disk has to be particularly smart or know a
lot about the data in order to optimise the head movement for
a load like this.

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: 2005-03-22 13:33    [W:0.115 / U:1.536 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site