![]() | ||||||||||
Messages in this thread |
Jens Axboe wrote on Friday, October 07, 2005 12:24 AM > I don't understand the need for this patch - the generic tagging is only > used if the SCSI LLD indicated it wanted it by issuing a > scsi_activate_tcq(). So blk_queue_start_tag() is only called if the LLD > already did a scsi_activate_tcq(), and blk_queue_end_tag() is only > called if the rq is block layer tagged. blk_queue_find_tag() is only > used with direct use of scsi_find_tag(), a function that should (and is) > only usable by users of the generic tagging already. > You beat me by a couple of minutes. I was about to say that the culprit is in the qla2x00 driver where it unnecessarily activated generic blk tag queuing by calling scsi_activate_tcq() and it never uses tag. > So please, a description of what problem you are trying to solve would > be appreciated :-) It starts out with scsi_end_request being a fairly hot function in the execution profile, then I noticed blk_queue_start/end_tag() are being called but no actual consumer of using the tag. I'm trying to find a way to avoid making these blk_queue_start/end_tag calls. I got the answer now. The proper way is to fix it in the scsi LLDD. Scratch this patch, new patch to follow :-) - Ken - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | |||||||||
| Last update: 2005-10-07 05:37 [W:0.131 / U:0.250 seconds] ©2003-2008 Jasper Spaans | ||||||||||