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| author | Jens Axboe <jens.axboe@oracle.com> | 2009-10-06 20:53:44 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2009-10-06 21:09:32 +0200 |
| commit | b9c8946b192397394a0ccd4fcecb31bc060f79f8 (patch) | |
| tree | 54169a387e8e4a5f6f79e06de6fbdd0096198069 /block/cfq-iosched.c | |
| parent | 0b182d617eb50762b483658dd6dd9a9fbcb25758 (diff) | |
| download | lwn-b9c8946b192397394a0ccd4fcecb31bc060f79f8.tar.gz lwn-b9c8946b192397394a0ccd4fcecb31bc060f79f8.zip | |
cfq-iosched: fix the slice residual sign
We should subtract the slice residual from the rb tree key, since
a negative residual count indicates that the cfqq overran its slice
the last time. Hence we want to add the overrun time, to position
it a bit further away in the service tree.
Reported-by: Corrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/cfq-iosched.c')
| -rw-r--r-- | block/cfq-iosched.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 5c3cee93329a..4ab33d8a20b2 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -507,8 +507,14 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, } else rb_key += jiffies; } else if (!add_front) { + /* + * Get our rb key offset. Subtract any residual slice + * value carried from last service. A negative resid + * count indicates slice overrun, and this should position + * the next service time further away in the tree. + */ rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; - rb_key += cfqq->slice_resid; + rb_key -= cfqq->slice_resid; cfqq->slice_resid = 0; } else { rb_key = -HZ; |