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[Qemu-devel] [PATCH 22/27] block/parallels: improve image reading perfor
From: |
Denis V. Lunev |
Subject: |
[Qemu-devel] [PATCH 22/27] block/parallels: improve image reading performance |
Date: |
Tue, 28 Apr 2015 10:46:55 +0300 |
Try to perform IO for the biggest continuous block possible.
The performance for sequential read is increased from 220 Mb/sec to
360 Mb/sec for continous image on my SSD HDD.
Signed-off-by: Denis V. Lunev <address@hidden>
Reviewed-by: Roman Kagan <address@hidden>
Reviewed-by: Stefan Hajnoczi <address@hidden>
CC: Kevin Wolf <address@hidden>
---
block/parallels.c | 36 +++++++++++++++++++++++++++++++-----
1 file changed, 31 insertions(+), 5 deletions(-)
diff --git a/block/parallels.c b/block/parallels.c
index 76e3a4e..5ff74e8 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -103,6 +103,35 @@ static int cluster_remainder(BDRVParallelsState *s,
int64_t sector_num,
return MIN(nb_sectors, ret);
}
+static int64_t block_status(BDRVParallelsState *s, int64_t sector_num,
+ int nb_sectors, int *pnum)
+{
+ int64_t start_off = -2, prev_end_off = -2;
+
+ *pnum = 0;
+ while (nb_sectors > 0 || start_off == -2) {
+ int64_t offset = seek_to_sector(s, sector_num);
+ int to_end;
+
+ if (start_off == -2) {
+ start_off = offset;
+ prev_end_off = offset;
+ } else if (offset != prev_end_off) {
+ break;
+ }
+
+ to_end = cluster_remainder(s, sector_num, nb_sectors);
+ nb_sectors -= to_end;
+ sector_num += to_end;
+ *pnum += to_end;
+
+ if (offset > 0) {
+ prev_end_off += to_end;
+ }
+ }
+ return start_off;
+}
+
static int64_t allocate_cluster(BlockDriverState *bs, int64_t sector_num)
{
BDRVParallelsState *s = bs->opaque;
@@ -148,11 +177,9 @@ static int64_t coroutine_fn
parallels_co_get_block_status(BlockDriverState *bs,
int64_t offset;
qemu_co_mutex_lock(&s->lock);
- offset = seek_to_sector(s, sector_num);
+ offset = block_status(s, sector_num, nb_sectors, pnum);
qemu_co_mutex_unlock(&s->lock);
- *pnum = cluster_remainder(s, sector_num, nb_sectors);
-
if (offset < 0) {
return 0;
}
@@ -218,10 +245,9 @@ static coroutine_fn int
parallels_co_readv(BlockDriverState *bs,
int n, nbytes;
qemu_co_mutex_lock(&s->lock);
- position = seek_to_sector(s, sector_num);
+ position = block_status(s, sector_num, nb_sectors, &n);
qemu_co_mutex_unlock(&s->lock);
- n = cluster_remainder(s, sector_num, nb_sectors);
nbytes = n << BDRV_SECTOR_BITS;
if (position < 0) {
--
1.9.1
- [Qemu-devel] [PATCH 13/27] parallels: change copyright information in the image header, (continued)
- [Qemu-devel] [PATCH 13/27] parallels: change copyright information in the image header, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 12/27] iotests, parallels: test for newly created parallels image via qemu-img, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 10/27] iotests, parallels: test for write into Parallels image, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 14/27] block/parallels: rename catalog_ names to bat_, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 15/27] block/parallels: create bat2sect helper, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 16/27] block/parallels: keep BAT bitmap data in little endian in memory, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 17/27] block/parallels: read parallels image header and BAT into single buffer, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 18/27] block/parallels: move parallels_open/probe to the very end of the file, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 19/27] block/parallels: implement parallels_check method of block driver, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 20/27] block/parallels: implement incorrect close detection, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 22/27] block/parallels: improve image reading performance,
Denis V. Lunev <=
- [Qemu-devel] [PATCH 21/27] iotests, parallels: check for incorrectly closed image in tests, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 23/27] block/parallels: create bat_entry_off helper, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 24/27] block/parallels: delay writing to BAT till bdrv_co_flush_to_os, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 25/27] block/parallels: add prealloc-mode and prealloc-size open paramemets, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 26/27] block/parallels: optimize linear image expansion, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 27/27] block/parallels: improve image writing performance further, Denis V. Lunev, 2015/04/28