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vhost: make poll group refcount per-session

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Change the way we increase poll group reference counts
for round-robin scheduling.

So far we used to increase them whenever someone called
vhost_get_poll_group() and this worked fine for Vhost-Block
which picks a new poll group for each session. Vhost-SCSI,
however, picks only one poll group for all sessions on
a vhost device. This means that some threads will have
multiple Vhost-SCSI pollers but will still appear to the
vhost scheduler as if they had only one.

To fix it, increase poll group refcnt only when sessions
are really being started - in vhost_session_start_done().

Change-Id: I60f0d2101239e5a91138a5afd30c51dc1ccf7c2e
Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/466733
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Vitaliy Mysak <vitaliy.mysak@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
This commit is contained in:
Darek Stojaczyk 2019-07-30 11:23:06 +02:00 committed by Jim Harris
parent 1eba43239e
commit 6e77b0b68d
4 changed files with 13 additions and 29 deletions
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18
lib/vhost/vhost.c
View File

@ -890,23 +890,18 @@ vhost_get_poll_group(struct spdk_cpuset *cpumask)
}
assert(selected_pg != NULL);
assert(selected_pg->ref < UINT_MAX);
selected_pg->ref++;
return selected_pg;
}
void
vhost_put_poll_group(struct vhost_poll_group *pg)
{
assert(pg->ref > 0);
pg->ref--;
}
void
vhost_session_start_done(struct spdk_vhost_session *vsession, int response)
{
if (response == 0) {
vsession->started = true;
assert(vsession->poll_group != NULL);
assert(vsession->poll_group->ref < UINT_MAX);
vsession->poll_group->ref++;
assert(vsession->vdev->active_session_num < UINT32_MAX);
vsession->vdev->active_session_num++;
}
@ -920,6 +915,11 @@ vhost_session_stop_done(struct spdk_vhost_session *vsession, int response)
{
if (response == 0) {
vsession->started = false;
assert(vsession->poll_group != NULL);
assert(vsession->poll_group->ref > 0);
vsession->poll_group->ref--;
vsession->poll_group = NULL;
assert(vsession->vdev->active_session_num > 0);
vsession->vdev->active_session_num--;
}

11
lib/vhost/vhost_blk.c
View File

@ -712,17 +712,10 @@ static int
vhost_blk_start(struct spdk_vhost_session *vsession)
{
struct vhost_poll_group *pg;
int rc;
pg = vhost_get_poll_group(vsession->vdev->cpumask);
rc = vhost_session_send_event(pg, vsession, vhost_blk_start_cb,
3, "start session");
if (rc != 0) {
vhost_put_poll_group(pg);
}
return rc;
return vhost_session_send_event(pg, vsession, vhost_blk_start_cb,
3, "start session");
}
static int

11
lib/vhost/vhost_nvme.c
View File

@ -1114,7 +1114,6 @@ static int
spdk_vhost_nvme_start(struct spdk_vhost_session *vsession)
{
struct vhost_poll_group *pg;
int rc;
if (vsession->vdev->active_session_num > 0) {
/* We're trying to start a second session */
@ -1123,14 +1122,8 @@ spdk_vhost_nvme_start(struct spdk_vhost_session *vsession)
}
pg = vhost_get_poll_group(vsession->vdev->cpumask);
rc = vhost_session_send_event(pg, vsession, spdk_vhost_nvme_start_cb,
3, "start session");
if (rc != 0) {
vhost_put_poll_group(pg);
}
return rc;
return vhost_session_send_event(pg, vsession, spdk_vhost_nvme_start_cb,
3, "start session");
}
static void

2
lib/vhost/vhost_scsi.c
View File

@ -1358,7 +1358,6 @@ vhost_scsi_start(struct spdk_vhost_session *vsession)
3, "start session");
if (rc != 0) {
if (svdev->vdev.active_session_num == 0) {
vhost_put_poll_group(svdev->poll_group);
svdev->poll_group = NULL;
}
}
@ -1459,7 +1458,6 @@ vhost_scsi_stop(struct spdk_vhost_session *vsession)
}
if (vsession->vdev->active_session_num == 0) {
vhost_put_poll_group(svsession->svdev->poll_group);
svsession->svdev->poll_group = NULL;
}
return 0;