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vdisk_blockio: Specify REQ_SYNC for synchronous I/O requests

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Using READ_SYNC instead of READ increases the priority of read requests.
Using WRITE_SYNC instead of REQ_WRITE increases the priority of write
requests and avoids that the CFQ scheduler queues such writes waiting
for further write requests.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>



git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@5411 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Vladislav Bolkhovitin
2014-04-09 23:58:20 +00:00
parent c664dcb277
commit 836481737a
1 changed files with 5 additions and 14 deletions
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scst/src/dev_handlers/scst_vdisk.c
+5 -14
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@@ -4566,7 +4566,7 @@ static ssize_t vdev_read_sync(struct scst_vdisk_dev *virt_dev, void *buf,
if (virt_dev->nullio)
return len;
else if (virt_dev->blockio)
return blockio_rw_sync(virt_dev, buf, len, loff, 0/*read*/);
return blockio_rw_sync(virt_dev, buf, len, loff, READ_SYNC);
else
return fileio_read_sync(virt_dev->fd, buf, len, loff);
}
@@ -4574,21 +4574,12 @@ static ssize_t vdev_read_sync(struct scst_vdisk_dev *virt_dev, void *buf,
static ssize_t vdev_write_sync(struct scst_vdisk_dev *virt_dev, void *buf,
size_t len, loff_t *loff)
{
int rw;
if (virt_dev->nullio) {
if (virt_dev->nullio)
return len;
} else if (virt_dev->blockio) {
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 36)
rw = REQ_WRITE;
#else
rw = 1 << BIO_RW;
#endif
return blockio_rw_sync(virt_dev, buf, len, loff, rw);
} else {
else if (virt_dev->blockio)
return blockio_rw_sync(virt_dev, buf, len, loff, WRITE_SYNC);
else
return fileio_write_sync(virt_dev->fd, buf, len, loff);
}
}
static enum compl_status_e vdev_exec_verify(struct vdisk_cmd_params *p)