On Wed, Oct 21, 2020 at 07:34:46PM -0500, Mike Christie wrote: > In-Reply-To: > > The following patches were made over Michael's vhost branch here: > > https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git/log/?h=vhost > > They fix a couple issues with vhost-scsi when we hit the 256 cmd limit > that result in the guest getting IO errors, add LUN reset support so > devices are not offlined during transient errors, allow us to manage > vhost scsi IO with cgroups, and imrpove IOPs up to 2X. > > The following patches are a follow up to this post: > https://patchwork.kernel.org/project/target-devel/cover/1600712588-9514-1-git-send-email-michael.christie@xxxxxxxxxx/ > which originally was fixing how vhost-scsi handled cmds so we would > not get IO errors when sending more than 256 cmds. > > In that patchset I needed to detect if a vq was in use and for this > patch: > https://patchwork.kernel.org/project/target-devel/patch/1600712588-9514-3-git-send-email-michael.christie@xxxxxxxxxx/ > It was suggested to add support for VHOST_RING_ENABLE. While doing > that though I hit a couple problems: > > 1. The patches moved how vhost-scsi allocated cmds from per lio > session to per vhost vq. To support both VHOST_RING_ENABLE and > where userspace didn't support it, I would have to keep around the > old per session/device cmd allocator/completion and then also maintain > the new code. Or, I would still have to use this patch > patchwork.kernel.org/cover/11790763/ for the compat case so there > adding the new ioctl would not help much. > > 2. For vhost-scsi I also wanted to prevent where we allocate iovecs > for 128 vqs even though we normally use a couple. To do this, I needed > something similar to #1, but the problem is that the VHOST_RING_ENABLE > call would come too late. > > To try and balance #1 and #2, these patches just allow vhost-scsi > to setup a vq when userspace starts to config it. This allows the > driver to only fully setup (we still waste some memory to support older > setups but do not have to preallocate everything like before) what > is used plus I do not need to maintain 2 code paths. OK, so could we get a patchset with just bugfixes for this release please? And features should go into next one ... > V3: > - fix compile errors > - fix possible crash where cmd could be freed while adding it to > completion list > - fix issue where we added the worker thread to the blk cgroup but > the blk IO was submitted by a driver workqueue. > > V2: > - fix use before set cpu var errors > - drop vhost_vq_is_setup > - include patches to do a worker thread per scsi IO vq >
