On Fri, Jun 09, 2023 at 09:49:39PM +0800, Xianting Tian wrote: > > 在 2023/6/9 下午9:41, Greg KH 写道: > > On Fri, Jun 09, 2023 at 03:39:24PM +0200, Greg KH wrote: > > > On Fri, Jun 09, 2023 at 09:18:15PM +0800, Xianting Tian wrote: > > > > From: Xianting Tian <tianxianting.txt@xxxxxxxxxxxxxxx> > > > > > > > > Cpu stall issue may happen if device is configured with multi queues > > > > and large queue depth, so fix it. > > > > > > > > Signed-off-by: Xianting Tian <xianting.tian@xxxxxxxxxxxxxxxxx> > > > > --- > > > > drivers/crypto/virtio/virtio_crypto_core.c | 1 + > > > > 1 file changed, 1 insertion(+) > > > > > > > > diff --git a/drivers/crypto/virtio/virtio_crypto_core.c b/drivers/crypto/virtio/virtio_crypto_core.c > > > > index 1198bd306365..94849fa3bd74 100644 > > > > --- a/drivers/crypto/virtio/virtio_crypto_core.c > > > > +++ b/drivers/crypto/virtio/virtio_crypto_core.c > > > > @@ -480,6 +480,7 @@ static void virtcrypto_free_unused_reqs(struct virtio_crypto *vcrypto) > > > > kfree(vc_req->req_data); > > > > kfree(vc_req->sgs); > > > > } > > > > + cond_resched(); > > > that's not "fixing a stall", it is "call the scheduler because we are > > > taking too long". The CPU isn't stalled at all, just busy. > > > > > > Are you sure this isn't just a bug in the code? Why is this code taking > > > so long that you have to force the scheduler to run? This is almost > > > always a sign that something else needs to be fixed instead. > > And same comment on the other 2 patches, please fix this properly. > > > > Also, this is a tight loop that is just freeing memory, why is it taking > > so long? Why do you want it to take longer (which is what you are doing > > here), ideally it would be faster, not slower, so you are now slowing > > down the system overall with this patchset, right? > > yes, it is the similar fix with one for virtio-net > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/net/virtio_net.c?h=v6.4-rc5&id=f8bb5104394560e29017c25bcade4c6b7aabd108 <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/net/virtio_net.c?h=v6.4-rc5&id=f8bb5104394560e29017c25bcade4c6b7aabd108> I would argue that this too is incorrect, because why does freeing memory take so long? And again, you are making it take longer, is that ok? thanks, greg k-h
