Hi, This is something I've been playing around and I have hopes of merging the core for 2.6.32, so I thought I'd send it out for some review and inspection. Basically this implements NAPI for block devices, and much of the core is essentially lifted from there. Since NAPI is already generic, there's a possibility for some code reuse too. It's pretty small though and there are a few small differences, so I just left it as-is for this posting. I've gotten good results with this on SSD devices, reducing the interrupt rate a lot. And that's just for single disks, if you had a bunch of those hanging off several controllers, it would look more interesting I'm sure. Apart from the core, I did patches for ahci and mpt. The former mostly as a proof of concept, it's been running my laptop and test box for months. There may be a problem with the ack part, as per the comment at the end of ahci_interrupt(). So far I haven't observed any bad behaviour. mpt is more interesting, as it's more geared at the market where this should make some impact. The mpt patch should also be fully stable, I've tested it on several platforms and adapters. As to results, they vary. On a faster box, I can reduce the interrupt rate by ~28% at only 50k IOPS. On a slower box, at 30k IOPS it'll drop by as much as 95%. Latencies numbers are as good (or better). On the faster box, the mpt controller even had interrupt coalescing enabled and it still made a big difference. Anyway, YMMV, I would appreciate some test results (and as usual, that even includes just saying that it boots and functions for you). If people feel adventurous, patches for other controllers will be happily queued up for testing. I may even be convinced to implement support for your controller of choice, if you have some fast storage hooked up and would like to experiment. Generally, adding support to a driver is not very hard and the two conversions included were also meant to serve as an inspiration. Patches are against current -git. You can also pull them from git://git.kernel.dk/linux-2.6-block.git blk-iopoll block/Makefile | 2 block/blk-iopoll.c | 227 +++++++++++++++++++++++++++++++ drivers/ata/ahci.c | 53 ++++++- drivers/message/fusion/mptbase.c | 99 +++++++++++-- drivers/message/fusion/mptbase.h | 3 include/linux/blk-iopoll.h | 41 +++++ include/linux/interrupt.h | 1 include/linux/libata.h | 2 kernel/sysctl.c | 10 + 9 files changed, 419 insertions(+), 19 deletions(-) -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
