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| author | Divyesh Shah <dpshah@google.com> | 2010-01-07 03:58:20 +0100 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2010-01-11 16:16:18 +0100 |
| commit | 875feb63b9567442be73efbcc9a8470e376d6423 (patch) | |
| tree | 554331e9634a5327daa755bb1b3338697866018b /block | |
| parent | genhd: overlapping variable definition (diff) | |
| download | linux-875feb63b9567442be73efbcc9a8470e376d6423.tar.xz linux-875feb63b9567442be73efbcc9a8470e376d6423.zip | |
cfq-iosched: Respect ioprio_class when preempting
In cfq_should_preempt(), we currently allow some cases where a non-RT request
can preempt an ongoing RT cfqq timeslice. This should not happen.
Examples include:
o A sync_noidle wl type non-RT request pre-empting a sync_noidle wl type cfqq
on which we are idling.
o Once we have per-cgroup async queues, a non-RT sync request pre-empting a RT
async cfqq.
Signed-off-by: Divyesh Shah<dpshah@google.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/cfq-iosched.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 918c7fd9aeb1..ee130f14d1fc 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3077,6 +3077,12 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, return true; /* + * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice. + */ + if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq)) + return false; + + /* * if the new request is sync, but the currently running queue is * not, let the sync request have priority. */ |