From: Jeff Moyer <jmoyer@redhat.com> Date: Tue, 15 Dec 2009 13:08:36 -0500 Subject: [block] iosched: reset batch for ordered requests Message-id: <1260882517-14489-2-git-send-email-jmoyer@redhat.com> Patchwork-id: 21950 O-Subject: [RHEL5 PATCH 1/2] Deadline iosched: Reset batch for ordered requests Bugzilla: 462472 RH-Acked-by: Vivek Goyal <vgoyal@redhat.com> fixes bug 462472 commit dfb3d72a9aa519672c9ae06f0d2f93eccb35482f Author: Aaron Carroll <aaronc@gelato.unsw.edu.au> Date: Tue Oct 30 10:40:13 2007 +0100 Deadline iosched: Reset batch for ordered requests The deadline I/O scheduler does not reset the batch count when starting a new batch at a higher-sectored request. This means the second and subsequent batch in the same data direction will never exceed a single request in size whenever higher-sectored requests are pending. This patch gives new batches in the same data direction as old ones their full quota of requests by resetting the batch count. Signed-off-by: Aaron Carroll <aaronc@gelato.unsw.edu.au> Signed-off-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Jeff Moyer <jmoyer@redhat.com> diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c index c7ca9f0..fcf0482 100644 --- a/block/deadline-iosched.c +++ b/block/deadline-iosched.c @@ -522,12 +522,11 @@ dispatch_writes: dispatch_find_request: /* * we are not running a batch, find best request for selected data_dir + * and start a new batch */ if (deadline_check_fifo(dd, data_dir)) { /* An expired request exists - satisfy it */ - dd->batching = 0; drq = list_entry_fifo(dd->fifo_list[data_dir].next); - } else if (dd->next_drq[data_dir]) { /* * The last req was the same dir and we have a next request in @@ -540,10 +539,11 @@ dispatch_find_request: * higher-sectored requests. Go back to the lowest sectored * request (1 way elevator) and start a new batch. */ - dd->batching = 0; drq = deadline_find_first_drq(dd, data_dir); } + dd->batching = 0; + dispatch_request: /* * drq is the selected appropriate request.