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block: disable I/O throttling on sync api 

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Zhi Yong Wu 2012-04-02 18:59:34 +08:00 committed by Kevin Wolf
parent 43cf8ae69b
commit 498e386c58
1 changed files with 20 additions and 0 deletions
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20
block.c
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@ -1463,6 +1463,17 @@ static int bdrv_rw_co(BlockDriverState *bs, int64_t sector_num, uint8_t *buf,
qemu_iovec_init_external(&qiov, &iov, 1);
/**
* In sync call context, when the vcpu is blocked, this throttling timer
* will not fire; so the I/O throttling function has to be disabled here
* if it has been enabled.
*/
if (bs->io_limits_enabled) {
fprintf(stderr, "Disabling I/O throttling on '%s' due "
"to synchronous I/O.\n", bdrv_get_device_name(bs));
bdrv_io_limits_disable(bs);
}
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_rw_co_entry(&rwco);
@ -1969,10 +1980,19 @@ static int guess_disk_lchs(BlockDriverState *bs,
struct partition *p;
uint32_t nr_sects;
uint64_t nb_sectors;
bool enabled;
bdrv_get_geometry(bs, &nb_sectors);
/**
* The function will be invoked during startup not only in sync I/O mode,
* but also in async I/O mode. So the I/O throttling function has to
* be disabled temporarily here, not permanently.
*/
enabled = bs->io_limits_enabled;
bs->io_limits_enabled = false;
ret = bdrv_read(bs, 0, buf, 1);
bs->io_limits_enabled = enabled;
if (ret < 0)
return -1;
/* test msdos magic */