Messages in this thread Patch in this message | | | Subject | Re: [patch]block cfq: select new workload if priority changed | From | Shaohua Li <> | Date | Mon, 13 Dec 2010 08:39:52 +0800 |
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On Fri, 2010-12-10 at 22:56 +0800, Jeff Moyer wrote: > Shaohua Li <shaohua.li@intel.com> writes: > > > If priority is changed, continue checking workload_expires and service tree > > count of previous workload is meaningless. We should always choose the workload > > I'd change that first sentence to: > > If priority is changed, continuing to check workload_expires and > service tree count of the previous workload does not make sense. > > > with lowest key of new priority in such case. > > > > Signed-off-by: Shaohua Li <shaohua.li@intel.com> > > This makes sense to me. > > Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Thanks, modified the the changelog.
If priority is changed, continuing to check workload_expires and service tree count of the previous workload does not make sense. We should always choose the workload with lowest key of new priority in such case.
Signed-off-by: Shaohua Li <shaohua.li@intel.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> --- block/cfq-iosched.c | 5 +++++ 1 file changed, 5 insertions(+)
Index: linux/block/cfq-iosched.c =================================================================== --- linux.orig/block/cfq-iosched.c 2010-12-08 19:39:01.000000000 +0800 +++ linux/block/cfq-iosched.c 2010-12-09 10:27:24.000000000 +0800 @@ -2116,6 +2116,7 @@ static void choose_service_tree(struct c unsigned count; struct cfq_rb_root *st; unsigned group_slice; + enum wl_prio_t original_prio = cfqd->serving_prio; if (!cfqg) { cfqd->serving_prio = IDLE_WORKLOAD; @@ -2134,6 +2135,9 @@ static void choose_service_tree(struct c return; } + if (original_prio != cfqd->serving_prio) + goto new_workload; + /* * For RT and BE, we have to choose also the type * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload @@ -2148,6 +2152,7 @@ static void choose_service_tree(struct c if (count && !time_after(jiffies, cfqd->workload_expires)) return; +new_workload: /* otherwise select new workload type */ cfqd->serving_type = cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
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