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[Qemu-devel] [PATCH 21/26] stream: fix ratelimiting corner case
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 21/26] stream: fix ratelimiting corner case |
Date: |
Thu, 12 Apr 2012 14:01:11 +0200 |
This fixes inability to make progress in streaming if the quota
is set to less than the amount of data that an I/O operation has
to write.
In this case, limit->dispatched + n will always be above the
quota and, due to the "goto retry" to recheck cancellation and
allocation, streaming will livelock.
Signed-off-by: Paolo Bonzini <address@hidden>
---
block/stream.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/block/stream.c b/block/stream.c
index 2b492d5..b76104c 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -33,19 +33,19 @@ typedef struct {
static int64_t ratelimit_calculate_delay(RateLimit *limit, uint64_t n)
{
- int64_t delay_ns = 0;
int64_t now = qemu_get_clock_ns(rt_clock);
if (limit->next_slice_time < now) {
limit->next_slice_time = now + SLICE_TIME;
limit->dispatched = 0;
}
- if (limit->dispatched + n > limit->slice_quota) {
- delay_ns = limit->next_slice_time - now;
- } else {
+ if (limit->dispatched == 0 || limit->dispatched + n <= limit->slice_quota)
{
limit->dispatched += n;
+ return 0;
+ } else {
+ limit->dispatched = n;
+ return limit->next_slice_time - now;
}
- return delay_ns;
}
static void ratelimit_set_speed(RateLimit *limit, uint64_t speed)
--
1.7.9.3
- [Qemu-devel] [PATCH 12/26] block: update in-memory backing file and format, (continued)
- [Qemu-devel] [PATCH 12/26] block: update in-memory backing file and format, Paolo Bonzini, 2012/04/12
- [Qemu-devel] [PATCH 11/26] block: push bdrv_change_backing_file error checking up from drivers, Paolo Bonzini, 2012/04/12
- [Qemu-devel] [PATCH 13/26] block: open backing file as read-only when probing for size, Paolo Bonzini, 2012/04/12
- [Qemu-devel] [PATCH 22/26] stream: do not copy unallocated sectors from the base, Paolo Bonzini, 2012/04/12
- [Qemu-devel] [PATCH 23/26] block: implement is_allocated for raw, Paolo Bonzini, 2012/04/12
- [Qemu-devel] [PATCH 24/26] stream: tweak usage of bdrv_co_is_allocated, Paolo Bonzini, 2012/04/12
- [Qemu-devel] [PATCH 16/26] qemu-io: correctly print non-integer values as decimals, Paolo Bonzini, 2012/04/12
- [Qemu-devel] [PATCH 25/26] stream: move is_allocated_above to block.c, Paolo Bonzini, 2012/04/12
- [Qemu-devel] [PATCH 17/26] qemu-io: fix the alloc command, Paolo Bonzini, 2012/04/12
- [Qemu-devel] [PATCH 15/26] qemu-iotests: strip spaces from qemu-img/qemu-io/qemu command lines, Paolo Bonzini, 2012/04/12
- [Qemu-devel] [PATCH 21/26] stream: fix ratelimiting corner case,
Paolo Bonzini <=
- [Qemu-devel] [PATCH 18/26] stream: fix sectors not allocated test, Paolo Bonzini, 2012/04/12
- [Qemu-devel] [PATCH 19/26] stream: add testcase for partial streaming, Paolo Bonzini, 2012/04/12
- [Qemu-devel] [PATCH 26/26] stream: move rate limiting to a separate header file, Paolo Bonzini, 2012/04/12
- [Qemu-devel] [PATCH 20/26] stream: pass new base image format to bdrv_change_backing_file, Paolo Bonzini, 2012/04/12
- [Qemu-devel] [PATCH 27/26] block: another bdrv_append fix, Paolo Bonzini, 2012/04/17