<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/drivers/vhost/scsi.c, branch v5.11</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>vhost scsi: fix error return code in vhost_scsi_set_endpoint()</title>
<updated>2020-12-18T21:14:31+00:00</updated>
<author>
<name>Zhang Changzhong</name>
<email>zhangchangzhong@huawei.com</email>
</author>
<published>2020-12-04T08:43:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=2e1139d613c7fb0956e82f72a8281c0a475ad4f8'/>
<id>2e1139d613c7fb0956e82f72a8281c0a475ad4f8</id>
<content type='text'>
Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: 25b98b64e284 ("vhost scsi: alloc cmds per vq instead of session")
Reported-by: Hulk Robot &lt;hulkci@huawei.com&gt;
Signed-off-by: Zhang Changzhong &lt;zhangchangzhong@huawei.com&gt;
Link: https://lore.kernel.org/r/1607071411-33484-1-git-send-email-zhangchangzhong@huawei.com
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: 25b98b64e284 ("vhost scsi: alloc cmds per vq instead of session")
Reported-by: Hulk Robot &lt;hulkci@huawei.com&gt;
Signed-off-by: Zhang Changzhong &lt;zhangchangzhong@huawei.com&gt;
Link: https://lore.kernel.org/r/1607071411-33484-1-git-send-email-zhangchangzhong@huawei.com
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>vhost scsi: fix lun reset completion handling</title>
<updated>2020-11-25T09:22:13+00:00</updated>
<author>
<name>Mike Christie</name>
<email>michael.christie@oracle.com</email>
</author>
<published>2020-11-20T15:50:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=b4fffc177fad3c99ee049611a508ca9561bb6871'/>
<id>b4fffc177fad3c99ee049611a508ca9561bb6871</id>
<content type='text'>
vhost scsi owns the scsi se_cmd but lio frees the se_cmd-&gt;se_tmr
before calling release_cmd, so while with normal cmd completion we
can access the se_cmd from the vhost work, we can't do the same with
se_cmd-&gt;se_tmr. This has us copy the tmf response in
vhost_scsi_queue_tm_rsp to our internal vhost-scsi tmf struct for
when it gets sent to the guest from our worker thread.

Fixes: efd838fec17b ("vhost scsi: Add support for LUN resets.")
Signed-off-by: Mike Christie &lt;michael.christie@oracle.com&gt;
Acked-by: Stefan Hajnoczi &lt;stefanha@redhat.com&gt;
Link: https://lore.kernel.org/r/1605887459-3864-1-git-send-email-michael.christie@oracle.com
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
vhost scsi owns the scsi se_cmd but lio frees the se_cmd-&gt;se_tmr
before calling release_cmd, so while with normal cmd completion we
can access the se_cmd from the vhost work, we can't do the same with
se_cmd-&gt;se_tmr. This has us copy the tmf response in
vhost_scsi_queue_tm_rsp to our internal vhost-scsi tmf struct for
when it gets sent to the guest from our worker thread.

Fixes: efd838fec17b ("vhost scsi: Add support for LUN resets.")
Signed-off-by: Mike Christie &lt;michael.christie@oracle.com&gt;
Acked-by: Stefan Hajnoczi &lt;stefanha@redhat.com&gt;
Link: https://lore.kernel.org/r/1605887459-3864-1-git-send-email-michael.christie@oracle.com
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>vhost scsi: Add support for LUN resets.</title>
<updated>2020-11-15T22:30:55+00:00</updated>
<author>
<name>Mike Christie</name>
<email>michael.christie@oracle.com</email>
</author>
<published>2020-11-10T05:33:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=efd838fec17bd8756da852a435800a7e6281bfbc'/>
<id>efd838fec17bd8756da852a435800a7e6281bfbc</id>
<content type='text'>
In newer versions of virtio-scsi we just reset the timer when an a
command times out, so TMFs are never sent for the cmd time out case.
However, in older kernels and for the TMF inject cases, we can still get
resets and we end up just failing immediately so the guest might see the
device get offlined and IO errors.

For the older kernel cases, we want the same end result as the
modern virtio-scsi driver where we let the lower levels fire their error
handling and handle the problem. And at the upper levels we want to
wait. This patch ties the LUN reset handling into the LIO TMF code which
will just wait for outstanding commands to complete like we are doing in
the modern virtio-scsi case.

Note: I did not handle the ABORT case to keep this simple. For ABORTs
LIO just waits on the cmd like how it does for the RESET case. If
an ABORT fails, the guest OS ends up escalating to LUN RESET, so in
the end we get the same behavior where we wait on the outstanding
cmds.

Signed-off-by: Mike Christie &lt;michael.christie@oracle.com&gt;
Link: https://lore.kernel.org/r/1604986403-4931-6-git-send-email-michael.christie@oracle.com
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Acked-by: Stefan Hajnoczi &lt;stefanha@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In newer versions of virtio-scsi we just reset the timer when an a
command times out, so TMFs are never sent for the cmd time out case.
However, in older kernels and for the TMF inject cases, we can still get
resets and we end up just failing immediately so the guest might see the
device get offlined and IO errors.

For the older kernel cases, we want the same end result as the
modern virtio-scsi driver where we let the lower levels fire their error
handling and handle the problem. And at the upper levels we want to
wait. This patch ties the LUN reset handling into the LIO TMF code which
will just wait for outstanding commands to complete like we are doing in
the modern virtio-scsi case.

Note: I did not handle the ABORT case to keep this simple. For ABORTs
LIO just waits on the cmd like how it does for the RESET case. If
an ABORT fails, the guest OS ends up escalating to LUN RESET, so in
the end we get the same behavior where we wait on the outstanding
cmds.

Signed-off-by: Mike Christie &lt;michael.christie@oracle.com&gt;
Link: https://lore.kernel.org/r/1604986403-4931-6-git-send-email-michael.christie@oracle.com
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Acked-by: Stefan Hajnoczi &lt;stefanha@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>vhost scsi: add lun parser helper</title>
<updated>2020-11-15T22:30:55+00:00</updated>
<author>
<name>Mike Christie</name>
<email>michael.christie@oracle.com</email>
</author>
<published>2020-11-10T05:33:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=18f1becb6948cd411fd01968a0a54af63732e73c'/>
<id>18f1becb6948cd411fd01968a0a54af63732e73c</id>
<content type='text'>
Move code to parse lun from req's lun_buf to helper, so tmf code
can use it in the next patch.

Signed-off-by: Mike Christie &lt;michael.christie@oracle.com&gt;
Reviewed-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Acked-by: Jason Wang &lt;jasowang@redhat.com&gt;
Link: https://lore.kernel.org/r/1604986403-4931-5-git-send-email-michael.christie@oracle.com
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Acked-by: Stefan Hajnoczi &lt;stefanha@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Move code to parse lun from req's lun_buf to helper, so tmf code
can use it in the next patch.

Signed-off-by: Mike Christie &lt;michael.christie@oracle.com&gt;
Reviewed-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Acked-by: Jason Wang &lt;jasowang@redhat.com&gt;
Link: https://lore.kernel.org/r/1604986403-4931-5-git-send-email-michael.christie@oracle.com
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Acked-by: Stefan Hajnoczi &lt;stefanha@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>vhost scsi: fix cmd completion race</title>
<updated>2020-11-15T22:30:55+00:00</updated>
<author>
<name>Mike Christie</name>
<email>michael.christie@oracle.com</email>
</author>
<published>2020-11-10T05:33:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=47a3565e8bb14ec48a75b48daf57aa830e2691f8'/>
<id>47a3565e8bb14ec48a75b48daf57aa830e2691f8</id>
<content type='text'>
We might not do the final se_cmd put from vhost_scsi_complete_cmd_work.
When the last put happens a little later then we could race where
vhost_scsi_complete_cmd_work does vhost_signal, the guest runs and sends
more IO, and vhost_scsi_handle_vq runs but does not find any free cmds.

This patch has us delay completing the cmd until the last lio core ref
is dropped. We then know that once we signal to the guest that the cmd
is completed that if it queues a new command it will find a free cmd.

Signed-off-by: Mike Christie &lt;michael.christie@oracle.com&gt;
Reviewed-by: Maurizio Lombardi &lt;mlombard@redhat.com&gt;
Link: https://lore.kernel.org/r/1604986403-4931-4-git-send-email-michael.christie@oracle.com
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Acked-by: Stefan Hajnoczi &lt;stefanha@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We might not do the final se_cmd put from vhost_scsi_complete_cmd_work.
When the last put happens a little later then we could race where
vhost_scsi_complete_cmd_work does vhost_signal, the guest runs and sends
more IO, and vhost_scsi_handle_vq runs but does not find any free cmds.

This patch has us delay completing the cmd until the last lio core ref
is dropped. We then know that once we signal to the guest that the cmd
is completed that if it queues a new command it will find a free cmd.

Signed-off-by: Mike Christie &lt;michael.christie@oracle.com&gt;
Reviewed-by: Maurizio Lombardi &lt;mlombard@redhat.com&gt;
Link: https://lore.kernel.org/r/1604986403-4931-4-git-send-email-michael.christie@oracle.com
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Acked-by: Stefan Hajnoczi &lt;stefanha@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>vhost scsi: alloc cmds per vq instead of session</title>
<updated>2020-11-15T22:30:55+00:00</updated>
<author>
<name>Mike Christie</name>
<email>michael.christie@oracle.com</email>
</author>
<published>2020-11-10T05:33:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=25b98b64e28423b0769313dcaf96423836b1f93d'/>
<id>25b98b64e28423b0769313dcaf96423836b1f93d</id>
<content type='text'>
We currently are limited to 256 cmds per session. This leads to problems
where if the user has increased virtqueue_size to more than 2 or
cmd_per_lun to more than 256 vhost_scsi_get_tag can fail and the guest
will get IO errors.

This patch moves the cmd allocation to per vq so we can easily match
whatever the user has specified for num_queues and
virtqueue_size/cmd_per_lun. It also makes it easier to control how much
memory we preallocate. For cases, where perf is not as important and
we can use the current defaults (1 vq and 128 cmds per vq) memory use
from preallocate cmds is cut in half. For cases, where we are willing
to use more memory for higher perf, cmd mem use will now increase as
the num queues and queue depth increases.

Signed-off-by: Mike Christie &lt;michael.christie@oracle.com&gt;
Link: https://lore.kernel.org/r/1604986403-4931-3-git-send-email-michael.christie@oracle.com
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Reviewed-by: Maurizio Lombardi &lt;mlombard@redhat.com&gt;
Acked-by: Stefan Hajnoczi &lt;stefanha@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We currently are limited to 256 cmds per session. This leads to problems
where if the user has increased virtqueue_size to more than 2 or
cmd_per_lun to more than 256 vhost_scsi_get_tag can fail and the guest
will get IO errors.

This patch moves the cmd allocation to per vq so we can easily match
whatever the user has specified for num_queues and
virtqueue_size/cmd_per_lun. It also makes it easier to control how much
memory we preallocate. For cases, where perf is not as important and
we can use the current defaults (1 vq and 128 cmds per vq) memory use
from preallocate cmds is cut in half. For cases, where we are willing
to use more memory for higher perf, cmd mem use will now increase as
the num queues and queue depth increases.

Signed-off-by: Mike Christie &lt;michael.christie@oracle.com&gt;
Link: https://lore.kernel.org/r/1604986403-4931-3-git-send-email-michael.christie@oracle.com
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Reviewed-by: Maurizio Lombardi &lt;mlombard@redhat.com&gt;
Acked-by: Stefan Hajnoczi &lt;stefanha@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>vhost/scsi: fix up req type endian-ness</title>
<updated>2020-07-29T17:24:30+00:00</updated>
<author>
<name>Michael S. Tsirkin</name>
<email>mst@redhat.com</email>
</author>
<published>2020-07-10T10:36:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=295c1b9852d000580786375304a9800bd9634d15'/>
<id>295c1b9852d000580786375304a9800bd9634d15</id>
<content type='text'>
vhost/scsi doesn't handle type conversion correctly
for request type when using virtio 1.0 and up for BE,
or cross-endian platforms.

Fix it up using vhost_32_to_cpu.

Cc: stable@vger.kernel.org
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Acked-by: Jason Wang &lt;jasowang@redhat.com&gt;
Reviewed-by: Stefan Hajnoczi &lt;stefanha@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
vhost/scsi doesn't handle type conversion correctly
for request type when using virtio 1.0 and up for BE,
or cross-endian platforms.

Fix it up using vhost_32_to_cpu.

Cc: stable@vger.kernel.org
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Acked-by: Jason Wang &lt;jasowang@redhat.com&gt;
Reviewed-by: Stefan Hajnoczi &lt;stefanha@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost</title>
<updated>2020-06-10T20:42:09+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-06-10T20:42:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=09102704c67457c6cdea6c0394c34843484a852c'/>
<id>09102704c67457c6cdea6c0394c34843484a852c</id>
<content type='text'>
Pull virtio updates from Michael Tsirkin:

 - virtio-mem: paravirtualized memory hotplug

 - support doorbell mapping for vdpa

 - config interrupt support in ifc

 - fixes all over the place

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (40 commits)
  vhost/test: fix up after API change
  virtio_mem: convert device block size into 64bit
  virtio-mem: drop unnecessary initialization
  ifcvf: implement config interrupt in IFCVF
  vhost: replace -1 with VHOST_FILE_UNBIND in ioctls
  vhost_vdpa: Support config interrupt in vdpa
  ifcvf: ignore continuous setting same status value
  virtio-mem: Don't rely on implicit compiler padding for requests
  virtio-mem: Try to unplug the complete online memory block first
  virtio-mem: Use -ETXTBSY as error code if the device is busy
  virtio-mem: Unplug subblocks right-to-left
  virtio-mem: Drop manual check for already present memory
  virtio-mem: Add parent resource for all added "System RAM"
  virtio-mem: Better retry handling
  virtio-mem: Offline and remove completely unplugged memory blocks
  mm/memory_hotplug: Introduce offline_and_remove_memory()
  virtio-mem: Allow to offline partially unplugged memory blocks
  mm: Allow to offline unmovable PageOffline() pages via MEM_GOING_OFFLINE
  virtio-mem: Paravirtualized memory hotunplug part 2
  virtio-mem: Paravirtualized memory hotunplug part 1
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull virtio updates from Michael Tsirkin:

 - virtio-mem: paravirtualized memory hotplug

 - support doorbell mapping for vdpa

 - config interrupt support in ifc

 - fixes all over the place

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (40 commits)
  vhost/test: fix up after API change
  virtio_mem: convert device block size into 64bit
  virtio-mem: drop unnecessary initialization
  ifcvf: implement config interrupt in IFCVF
  vhost: replace -1 with VHOST_FILE_UNBIND in ioctls
  vhost_vdpa: Support config interrupt in vdpa
  ifcvf: ignore continuous setting same status value
  virtio-mem: Don't rely on implicit compiler padding for requests
  virtio-mem: Try to unplug the complete online memory block first
  virtio-mem: Use -ETXTBSY as error code if the device is busy
  virtio-mem: Unplug subblocks right-to-left
  virtio-mem: Drop manual check for already present memory
  virtio-mem: Add parent resource for all added "System RAM"
  virtio-mem: Better retry handling
  virtio-mem: Offline and remove completely unplugged memory blocks
  mm/memory_hotplug: Introduce offline_and_remove_memory()
  virtio-mem: Allow to offline partially unplugged memory blocks
  mm: Allow to offline unmovable PageOffline() pages via MEM_GOING_OFFLINE
  virtio-mem: Paravirtualized memory hotunplug part 2
  virtio-mem: Paravirtualized memory hotunplug part 1
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi</title>
<updated>2020-06-05T22:11:50+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-06-05T22:11:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=818dbde78e0f4f11c9f804c36913a7ccfc2e87ad'/>
<id>818dbde78e0f4f11c9f804c36913a7ccfc2e87ad</id>
<content type='text'>
Pull SCSI updates from James Bottomley:
 :This series consists of the usual driver updates (qla2xxx, ufs, zfcp,
  target, scsi_debug, lpfc, qedi, qedf, hisi_sas, mpt3sas) plus a host
  of other minor updates.

  There are no major core changes in this series apart from a
  refactoring in scsi_lib.c"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (207 commits)
  scsi: ufs: ti-j721e-ufs: Fix unwinding of pm_runtime changes
  scsi: cxgb3i: Fix some leaks in init_act_open()
  scsi: ibmvscsi: Make some functions static
  scsi: iscsi: Fix deadlock on recovery path during GFP_IO reclaim
  scsi: ufs: Fix WriteBooster flush during runtime suspend
  scsi: ufs: Fix index of attributes query for WriteBooster feature
  scsi: ufs: Allow WriteBooster on UFS 2.2 devices
  scsi: ufs: Remove unnecessary memset for dev_info
  scsi: ufs-qcom: Fix scheduling while atomic issue
  scsi: mpt3sas: Fix reply queue count in non RDPQ mode
  scsi: lpfc: Fix lpfc_nodelist leak when processing unsolicited event
  scsi: target: tcmu: Fix a use after free in tcmu_check_expired_queue_cmd()
  scsi: vhost: Notify TCM about the maximum sg entries supported per command
  scsi: qla2xxx: Remove return value from qla_nvme_ls()
  scsi: qla2xxx: Remove an unused function
  scsi: iscsi: Register sysfs for iscsi workqueue
  scsi: scsi_debug: Parser tables and code interaction
  scsi: core: Refactor scsi_mq_setup_tags function
  scsi: core: Fix incorrect usage of shost_for_each_device
  scsi: qla2xxx: Fix endianness annotations in source files
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull SCSI updates from James Bottomley:
 :This series consists of the usual driver updates (qla2xxx, ufs, zfcp,
  target, scsi_debug, lpfc, qedi, qedf, hisi_sas, mpt3sas) plus a host
  of other minor updates.

  There are no major core changes in this series apart from a
  refactoring in scsi_lib.c"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (207 commits)
  scsi: ufs: ti-j721e-ufs: Fix unwinding of pm_runtime changes
  scsi: cxgb3i: Fix some leaks in init_act_open()
  scsi: ibmvscsi: Make some functions static
  scsi: iscsi: Fix deadlock on recovery path during GFP_IO reclaim
  scsi: ufs: Fix WriteBooster flush during runtime suspend
  scsi: ufs: Fix index of attributes query for WriteBooster feature
  scsi: ufs: Allow WriteBooster on UFS 2.2 devices
  scsi: ufs: Remove unnecessary memset for dev_info
  scsi: ufs-qcom: Fix scheduling while atomic issue
  scsi: mpt3sas: Fix reply queue count in non RDPQ mode
  scsi: lpfc: Fix lpfc_nodelist leak when processing unsolicited event
  scsi: target: tcmu: Fix a use after free in tcmu_check_expired_queue_cmd()
  scsi: vhost: Notify TCM about the maximum sg entries supported per command
  scsi: qla2xxx: Remove return value from qla_nvme_ls()
  scsi: qla2xxx: Remove an unused function
  scsi: iscsi: Register sysfs for iscsi workqueue
  scsi: scsi_debug: Parser tables and code interaction
  scsi: core: Refactor scsi_mq_setup_tags function
  scsi: core: Fix incorrect usage of shost_for_each_device
  scsi: qla2xxx: Fix endianness annotations in source files
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>vhost: allow device that does not depend on vhost worker</title>
<updated>2020-06-04T19:36:51+00:00</updated>
<author>
<name>Jason Wang</name>
<email>jasowang@redhat.com</email>
</author>
<published>2020-05-29T08:02:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=01fcb1cbc88effb3493c6197efc96b69b9f4823a'/>
<id>01fcb1cbc88effb3493c6197efc96b69b9f4823a</id>
<content type='text'>
vDPA device currently relays the eventfd via vhost worker. This is
inefficient due the latency of wakeup and scheduling, so this patch
tries to introduce a use_worker attribute for the vhost device. When
use_worker is not set with vhost_dev_init(), vhost won't try to
allocate a worker thread and the vhost_poll will be processed directly
in the wakeup function.

This help for vDPA since it reduces the latency caused by vhost worker.

In my testing, it saves 0.2 ms in pings between VMs on a mutual host.

Signed-off-by: Zhu Lingshan &lt;lingshan.zhu@intel.com&gt;
Signed-off-by: Jason Wang &lt;jasowang@redhat.com&gt;
Link: https://lore.kernel.org/r/20200529080303.15449-2-jasowang@redhat.com
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
vDPA device currently relays the eventfd via vhost worker. This is
inefficient due the latency of wakeup and scheduling, so this patch
tries to introduce a use_worker attribute for the vhost device. When
use_worker is not set with vhost_dev_init(), vhost won't try to
allocate a worker thread and the vhost_poll will be processed directly
in the wakeup function.

This help for vDPA since it reduces the latency caused by vhost worker.

In my testing, it saves 0.2 ms in pings between VMs on a mutual host.

Signed-off-by: Zhu Lingshan &lt;lingshan.zhu@intel.com&gt;
Signed-off-by: Jason Wang &lt;jasowang@redhat.com&gt;
Link: https://lore.kernel.org/r/20200529080303.15449-2-jasowang@redhat.com
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
