| Message ID | 1602104101-5592-1-git-send-email-michael.christie@oracle.com |
|---|---|
| Headers | show |
| Series | vhost: fix scsi cmd handling and IOPs | expand |
On Wed, Oct 07, 2020 at 03:54:45PM -0500, Mike Christie wrote: > 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 > > The patches also apply to Linus's or Martin's trees if you apply > https://patchwork.kernel.org/patch/11790681/ > which was merged into mst's tree already. > > The following patches are a follow up to this post: > https://patchwork.kernel.org/cover/11790763/ > 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/patch/11790685/ > 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. > > Note that in this posting I am also including additional patches > that create multiple vhost worker threads, because I wanted to see > if people felt that maybe to support that and for this enablement > issue we want a completely a new ioctl. > > > V2: > - fix use before set cpu var errors > - drop vhost_vq_is_setup > - include patches to do a worker thread per scsi IO vq Stefan, Paolo, Jason any input?
On 10/23/20 10:46 AM, Michael S. Tsirkin wrote: > On Wed, Oct 07, 2020 at 03:54:45PM -0500, Mike Christie wrote: >> The following patches were made over Michael's vhost branch here: >> https://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git/log/?h=vhost__;!!GqivPVa7Brio!IVNw3V-uPEJyaYcHGpZrPo_0vnAuPXchguJJZG5qCapOYzR8bOwuFyTZf49rMcokFOMG$ >> >> The patches also apply to Linus's or Martin's trees if you apply >> https://urldefense.com/v3/__https://patchwork.kernel.org/patch/11790681/__;!!GqivPVa7Brio!IVNw3V-uPEJyaYcHGpZrPo_0vnAuPXchguJJZG5qCapOYzR8bOwuFyTZf49rMfl3id0D$ >> which was merged into mst's tree already. >> >> The following patches are a follow up to this post: >> https://urldefense.com/v3/__https://patchwork.kernel.org/cover/11790763/__;!!GqivPVa7Brio!IVNw3V-uPEJyaYcHGpZrPo_0vnAuPXchguJJZG5qCapOYzR8bOwuFyTZf49rMWyfBwDA$ >> 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://urldefense.com/v3/__https://patchwork.kernel.org/patch/11790685/__;!!GqivPVa7Brio!IVNw3V-uPEJyaYcHGpZrPo_0vnAuPXchguJJZG5qCapOYzR8bOwuFyTZf49rMWWcMjJi$ >> 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. >> >> Note that in this posting I am also including additional patches >> that create multiple vhost worker threads, because I wanted to see >> if people felt that maybe to support that and for this enablement >> issue we want a completely a new ioctl. >> >> >> V2: >> - fix use before set cpu var errors >> - drop vhost_vq_is_setup >> - include patches to do a worker thread per scsi IO vq > > Stefan, Paolo, Jason any input? > Just a FYI there is a updated version of this patchset here: https://patchwork.kernel.org/project/target-devel/list/?series=368487