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[22/27] block/parallels: improve image reading performance

Message ID 1426069701-1405-23-git-send-email-den@openvz.org
State New
Headers show

Commit Message

Denis V. Lunev March 11, 2015, 10:28 a.m. UTC 
Try to perform IO for the biggest continuous block possible.
The performance for sequential read is increased from 220 Gb/sec to
360 Gb/sec for continous image on my SSD HDD.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Roman Kagan <rkagan@parallels.com>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/parallels.c | 37 ++++++++++++++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 5 deletions(-)

Comments

Stefan Hajnoczi April 22, 2015, 2:11 p.m. UTC | #1 
On Wed, Mar 11, 2015 at 01:28:16PM +0300, Denis V. Lunev wrote:
> Try to perform IO for the biggest continuous block possible.
> The performance for sequential read is increased from 220 Gb/sec to
> 360 Gb/sec for continous image on my SSD HDD.

Please, can I have your SSD drive? :)

Did you mean MB/sec?

> Signed-off-by: Denis V. Lunev <den@openvz.org>
> Reviewed-by: Roman Kagan <rkagan@parallels.com>
> CC: Kevin Wolf <kwolf@redhat.com>
> CC: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  block/parallels.c | 37 ++++++++++++++++++++++++++++++++-----
>  1 file changed, 32 insertions(+), 5 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Denis V. Lunev April 22, 2015, 2:13 p.m. UTC | #2 
On 22/04/15 17:11, Stefan Hajnoczi wrote:
> On Wed, Mar 11, 2015 at 01:28:16PM +0300, Denis V. Lunev wrote:
>> Try to perform IO for the biggest continuous block possible.
>> The performance for sequential read is increased from 220 Gb/sec to
>> 360 Gb/sec for continous image on my SSD HDD.
> Please, can I have your SSD drive? :)
>
> Did you mean MB/sec?
yes... This was so wonderful to write these numbers.
I am dreaming.

OK, will fix that.

>> Signed-off-by: Denis V. Lunev <den@openvz.org>
>> Reviewed-by: Roman Kagan <rkagan@parallels.com>
>> CC: Kevin Wolf <kwolf@redhat.com>
>> CC: Stefan Hajnoczi <stefanha@redhat.com>
>> ---
>>   block/parallels.c | 37 ++++++++++++++++++++++++++++++++-----
>>   1 file changed, 32 insertions(+), 5 deletions(-)
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
diff mbox

Patch

diff --git a/block/parallels.c b/block/parallels.c
index 2605c1a..0f255fe 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -97,6 +97,35 @@  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;
@@ -134,11 +163,9 @@  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;
     }
@@ -202,8 +229,8 @@  static coroutine_fn int parallels_co_readv(BlockDriverState *bs,
 
     qemu_co_mutex_lock(&s->lock);
     while (nb_sectors > 0) {
-        int64_t position = seek_to_sector(s, sector_num);
-        int n = cluster_remainder(s, sector_num, nb_sectors);
+        int n;
+        int64_t position = block_status(s, sector_num, nb_sectors, &n);
         int nbytes = n << BDRV_SECTOR_BITS;
 
         if (position < 0) {