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| author | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2011-04-27 18:40:11 +0200 |
|---|---|---|
| committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2011-04-27 18:40:11 +0200 |
| commit | a19be5f0f073525306f6a4b000d90dc84065ed93 (patch) | |
| tree | 3c2b4f2dfda149838f0060d3f38c7494d8612f4d /drivers/block/xen-blkback | |
| parent | xen/blkback: Stick REQ_SYNC on WRITEs to deal with CFQ I/O scheduler. (diff) | |
| download | linux-a19be5f0f073525306f6a4b000d90dc84065ed93.tar.xz linux-a19be5f0f073525306f6a4b000d90dc84065ed93.zip | |
Revert "xen/blkback: Move the plugging/unplugging to a higher level."
This reverts commit 97961ef46b9b5a6a7c918a38b898a7b3e49869f4 b/c
we lose about 15% performance if we do the unplugging and the
end of the reading the ring buffer.
Diffstat (limited to 'drivers/block/xen-blkback')
| -rw-r--r-- | drivers/block/xen-blkback/blkback.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c index 8583b130499a..eb068d0b47ea 100644 --- a/drivers/block/xen-blkback/blkback.c +++ b/drivers/block/xen-blkback/blkback.c @@ -276,8 +276,6 @@ int xen_blkif_schedule(void *arg) printk(KERN_DEBUG "%s: started\n", current->comm); while (!kthread_should_stop()) { - struct blk_plug plug; - if (try_to_freeze()) continue; if (unlikely(vbd->size != vbd_sz(vbd))) @@ -294,13 +292,9 @@ int xen_blkif_schedule(void *arg) blkif->waiting_reqs = 0; smp_mb(); /* clear flag *before* checking for work */ - blk_start_plug(&plug); - if (do_block_io_op(blkif)) blkif->waiting_reqs = 1; - blk_finish_plug(&plug); - if (log_stats && time_after(jiffies, blkif->st_print)) print_stats(blkif); } @@ -553,6 +547,7 @@ static void dispatch_rw_block_io(struct blkif_st *blkif, struct bio *biolist[BLKIF_MAX_SEGMENTS_PER_REQUEST]; int i, nbio = 0; int operation; + struct blk_plug plug; switch (req->operation) { case BLKIF_OP_READ: @@ -665,9 +660,15 @@ static void dispatch_rw_block_io(struct blkif_st *blkif, */ atomic_set(&pending_req->pendcnt, nbio); + /* Get a reference count for the disk queue and start sending I/O */ + blk_start_plug(&plug); + for (i = 0; i < nbio; i++) submit_bio(operation, biolist[i]); + blk_finish_plug(&plug); + /* Let the I/Os go.. */ + if (operation == READ) blkif->st_rd_sect += preq.nr_sects; else if (operation == WRITE || operation == WRITE_BARRIER) |