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fuse: Optimize request_end() by not taking fiq->waitq.lock
We take global fiq->waitq.lock every time, when we are in this function, but interrupted requests are just small subset of all requests. This patch optimizes request_end() and makes it to take the lock when it's really needed. queue_interrupt() needs small change for that. After req is linked to interrupt list, we do smp_mb() and check for FR_FINISHED again. In case of FR_FINISHED bit has appeared, we remove req and leave the function: Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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parent
8da6e91832
commit
217316a601
1 changed files with 20 additions and 8 deletions
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@ -431,10 +431,16 @@ static void request_end(struct fuse_conn *fc, struct fuse_req *req)
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if (test_and_set_bit(FR_FINISHED, &req->flags))
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goto put_request;
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spin_lock(&fiq->waitq.lock);
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list_del_init(&req->intr_entry);
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spin_unlock(&fiq->waitq.lock);
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/*
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* test_and_set_bit() implies smp_mb() between bit
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* changing and below intr_entry check. Pairs with
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* smp_mb() from queue_interrupt().
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*/
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if (!list_empty(&req->intr_entry)) {
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spin_lock(&fiq->waitq.lock);
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list_del_init(&req->intr_entry);
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spin_unlock(&fiq->waitq.lock);
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}
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WARN_ON(test_bit(FR_PENDING, &req->flags));
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WARN_ON(test_bit(FR_SENT, &req->flags));
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if (test_bit(FR_BACKGROUND, &req->flags)) {
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@ -473,12 +479,18 @@ static void request_end(struct fuse_conn *fc, struct fuse_req *req)
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static void queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req)
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{
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spin_lock(&fiq->waitq.lock);
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if (test_bit(FR_FINISHED, &req->flags)) {
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spin_unlock(&fiq->waitq.lock);
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return;
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}
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if (list_empty(&req->intr_entry)) {
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list_add_tail(&req->intr_entry, &fiq->interrupts);
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/*
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* Pairs with smp_mb() implied by test_and_set_bit()
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* from request_end().
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*/
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smp_mb();
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if (test_bit(FR_FINISHED, &req->flags)) {
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list_del_init(&req->intr_entry);
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spin_unlock(&fiq->waitq.lock);
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return;
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}
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wake_up_locked(&fiq->waitq);
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kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
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}
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