[PATCH, RFC]: per queue request table, list

From: Jens Axboe (axboe@suse.de)
Date: Thu Apr 13 2000 - 18:13:14 EST

Next message: Steve Dodd: "[PATCH] 2.3.99x: SMP race in getblk()?"
Previous message: Rik van Riel: "Re: Performance data..."
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Hi,

I've done some experimentation to reduce contention on the io_request_lock
and (mainly) reduce the time spent searching the global request table
for a free entry.

The patch introduces request queue request tables (horrible sentence)
and stores free requests in a linked listed for O(1) retrieval. Much
of the areas that the io_request_lock were protecting, can now be
safely guarded with a per-queue spin lock.

Patch has been tested on SMP x86 with no signs of bad things happening,
only SCSI has been tested though (only IDE CD-ROM drives, no disks).
Approach with caution. That said, I'd love to see someone with the
beefy I/O hardware (LVM of RAID setup with multiple disks) give this a
decent bench.

Comments and suggestions welcome! Patch is against 2.3.99-pre6-2

-- * Jens Axboe <axboe@suse.de> * Linux CD/DVD-ROM, SuSE Labs * http://kernel.dk

text/plain attachment: request-queue.diff

- 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/

Next message: Steve Dodd: "[PATCH] 2.3.99x: SMP race in getblk()?"
Previous message: Rik van Riel: "Re: Performance data..."
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

This archive was generated by hypermail 2b29 : Sat Apr 15 2000 - 21:00:23 EST