diff options
| author | Michael S. Tsirkin <mst@redhat.com> | 2014-05-28 17:07:02 +0300 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2014-06-09 16:21:06 +0300 |
| commit | 98f9ca0a3faa99b7388578d55eccecf272be4038 (patch) | |
| tree | 991e7bc48ed0cb9da73aefe8cf454a54fcf96435 | |
| parent | 23cc5a991c7a9fb7e6d6550e65cee4f4173111c5 (diff) | |
vhost: replace rcu with mutex
All memory accesses are done under some VQ mutex.
So lock/unlock all VQs is a faster equivalent of synchronize_rcu()
for memory access changes.
Some guests cause a lot of these changes, so it's helpful
to make them faster.
Reported-by: "Gonglei (Arei)" <arei.gonglei@huawei.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
| -rw-r--r-- | drivers/vhost/vhost.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 78987e481bc6..1c05e6030d42 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -593,6 +593,7 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m) { struct vhost_memory mem, *newmem, *oldmem; unsigned long size = offsetof(struct vhost_memory, regions); + int i; if (copy_from_user(&mem, m, size)) return -EFAULT; @@ -619,7 +620,14 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m) oldmem = rcu_dereference_protected(d->memory, lockdep_is_held(&d->mutex)); rcu_assign_pointer(d->memory, newmem); - synchronize_rcu(); + + /* All memory accesses are done under some VQ mutex. + * So below is a faster equivalent of synchronize_rcu() + */ + for (i = 0; i < d->nvqs; ++i) { + mutex_lock(&d->vqs[i]->mutex); + mutex_unlock(&d->vqs[i]->mutex); + } kfree(oldmem); return 0; } |