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Revert "xen/blkback: Move the plugging/unplugging to a higher level."
This reverts commit 97961ef46b
b/c
we lose about 15% performance if we do the unplugging and the
end of the reading the ring buffer.
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parent
013c3ca184
commit
a19be5f0f0
@ -276,8 +276,6 @@ int xen_blkif_schedule(void *arg)
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printk(KERN_DEBUG "%s: started\n", current->comm);
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while (!kthread_should_stop()) {
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struct blk_plug plug;
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if (try_to_freeze())
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continue;
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if (unlikely(vbd->size != vbd_sz(vbd)))
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@ -294,13 +292,9 @@ int xen_blkif_schedule(void *arg)
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blkif->waiting_reqs = 0;
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smp_mb(); /* clear flag *before* checking for work */
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blk_start_plug(&plug);
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if (do_block_io_op(blkif))
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blkif->waiting_reqs = 1;
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blk_finish_plug(&plug);
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if (log_stats && time_after(jiffies, blkif->st_print))
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print_stats(blkif);
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}
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@ -553,6 +547,7 @@ static void dispatch_rw_block_io(struct blkif_st *blkif,
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struct bio *biolist[BLKIF_MAX_SEGMENTS_PER_REQUEST];
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int i, nbio = 0;
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int operation;
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struct blk_plug plug;
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switch (req->operation) {
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case BLKIF_OP_READ:
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@ -665,9 +660,15 @@ static void dispatch_rw_block_io(struct blkif_st *blkif,
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*/
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atomic_set(&pending_req->pendcnt, nbio);
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/* Get a reference count for the disk queue and start sending I/O */
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blk_start_plug(&plug);
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for (i = 0; i < nbio; i++)
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submit_bio(operation, biolist[i]);
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blk_finish_plug(&plug);
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/* Let the I/Os go.. */
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if (operation == READ)
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blkif->st_rd_sect += preq.nr_sects;
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else if (operation == WRITE || operation == WRITE_BARRIER)
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