Re: stochastic fair queueing in the elevator [Re: [BENCHMARK] 2.4.20-ck3 / aa / rmap with contest]

From: Nick Piggin (
Date: Mon Feb 10 2003 - 07:17:30 EST

Andrea Arcangeli wrote:

>On Mon, Feb 10, 2003 at 03:48:08AM -0800, 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.
>NOTE: first there is no seek at all in the benchmark we're talking
>about, no idea why you think there are seeks. This is not tiobench, this
>is bonnie sequential read.
Yes, Andrew obviously missed this... Anyway, could it be due to
a big stripe size and hitting more disks in the RAID? How does
a single SCSI disk perform here, Andrea?

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

This archive was generated by hypermail 2b29 : Sat Feb 15 2003 - 22:00:27 EST