On 9/7/22 02:40, Liu, Changpeng wrote:
-----Original Message-----
From: Stephen Hemminger <step...@networkplumber.org>
Sent: Wednesday, September 7, 2022 5:16 AM
To: Liu, Changpeng <changpeng....@intel.com>
Cc: dev@dpdk.org; Maxime Coquelin <maxime.coque...@redhat.com>; Xia,
Chenbo <chenbo....@intel.com>
Subject: Re: [PATCH] vhost: use try_lock in rte_vhost_vring_call
On Tue, 6 Sep 2022 10:22:25 +0800
Changpeng Liu <changpeng....@intel.com> wrote:
Note that this function is in data path, so the thread context
may not same as socket messages processing context, by using
try_lock here, users can have another try in case of VQ's access
lock is held by `vhost-events` thread.
Signed-off-by: Changpeng Liu <changpeng....@intel.com>
---
lib/vhost/vhost.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
index 60cb05a0ff..072d2acb7b 100644
--- a/lib/vhost/vhost.c
+++ b/lib/vhost/vhost.c
@@ -1329,7 +1329,11 @@ rte_vhost_vring_call(int vid, uint16_t vring_idx)
if (!vq)
return -1;
- rte_spinlock_lock(&vq->access_lock);
+ if (!rte_spinlock_trylock(&vq->access_lock)) {
+ VHOST_LOG_CONFIG(dev->ifname, DEBUG,
+ "failed to kick guest, virtqueue busy.\n");
+ return -1;
+ }
If it is a race, logging a message is not a good idea; the log will fill
with this noise.
Instead make it statistic that can be seen by xstats.
It's a DEBUG log, users can't see it in practice.
Having an xstat would enable live debugging & post-mortem analysis.
You can have both the stats and the debug log.
Regards,
Maxime
