From 0c09e4225c511ce1b0ebe22e45962f83d5145e66 Mon Sep 17 00:00:00 2001

Message-Id: <0c09e4225c511ce1b0ebe22e45962f83d5145e66@dist-git>

From: =?UTF-8?q?J=C3=A1n=20Tomko?= <jtomko@redhat.com>

Date: Fri, 10 Jun 2022 15:10:29 +0200

Subject: [PATCH] conf: virtiofs: add thread_pool element

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Add an element to configure the thread pool size:

...

<binary>

  <thread_pool size='16'/>

</binary>

...

https://bugzilla.redhat.com/show_bug.cgi?id=2072905

Signed-off-by: Ján Tomko <jtomko@redhat.com>

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

(cherry picked from commit 0df2e7df80452f81edbfeb0ee355235b533346a9)

Signed-off-by: Ján Tomko <jtomko@redhat.com>

https://bugzilla.redhat.com/show_bug.cgi?id=2079582

---

 docs/formatdomain.rst                             |  6 ++++++

 docs/schemas/domaincommon.rng                     |  9 +++++++++

 src/conf/domain_conf.c                            | 15 +++++++++++++++

 src/conf/domain_conf.h                            |  1 +

 .../qemuxml2argvdata/vhost-user-fs-fd-memory.xml  |  1 +

 5 files changed, 32 insertions(+)

diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst

index 17e89a0c0d..e6cf2ec083 100644

--- a/docs/formatdomain.rst

+++ b/docs/formatdomain.rst

@@ -3316,6 +3316,7 @@ A directory on the host that can be accessed directly from the guest.

             <cache mode='always'/>

             <sandbox mode='namespace'/>

             <lock posix='on' flock='on'/>

+            <thread_pool size='16'/>

          </binary>

          <source dir='/path'/>

          <target dir='mount_tag'/>

@@ -3449,6 +3450,11 @@ A directory on the host that can be accessed directly from the guest.

    ``chroot``, see the

    `virtiofsd documentation <https://qemu.readthedocs.io/en/latest/tools/virtiofsd.html>`__

    for more details. ( :since:`Since 7.2.0` )

+   Element ``thread_pool`` accepts one attribute ``size`` which defines the

+   maximum thread pool size. A value of "0" disables the pool.

+   The thread pool helps increase the number of requests in flight when used with

+   storage that has a higher latency.  However, it has an overhead, and so for

+   fast, low latency filesystems, it may be best to turn it off. ( :since:`Since 8.5.0` )

 ``source``

    The resource on the host that is being accessed in the guest. The ``name``

    attribute must be used with ``type='template'``, and the ``dir`` attribute

diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng

index c9c1529979..79c8979410 100644

--- a/docs/schemas/domaincommon.rng

+++ b/docs/schemas/domaincommon.rng

@@ -3064,6 +3064,15 @@

             </optional>

           </element>

         </optional>

+        <optional>

+          <element name="thread_pool">

+            <optional>

+              <attribute name="size">

+                <data type="integer"/>

+              </attribute>

+            </optional>

+          </element>

+        </optional>

       </interleave>

     </element>

   </define>

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c

index 92510973e6..95afd9226e 100644

--- a/src/conf/domain_conf.c

+++ b/src/conf/domain_conf.c

@@ -2447,6 +2447,8 @@ virDomainFSDefNew(virDomainXMLOption *xmlopt)

     ret->src = virStorageSourceNew();

+    ret->thread_pool_size = -1;

+

     if (xmlopt &&

         xmlopt->privateData.fsNew &&

         !(ret->privateData = xmlopt->privateData.fsNew()))

@@ -9869,6 +9871,7 @@ virDomainFSDefParseXML(virDomainXMLOption *xmlopt,

     if (def->fsdriver == VIR_DOMAIN_FS_DRIVER_TYPE_VIRTIOFS) {

         g_autofree char *queue_size = virXPathString("string(./driver/@queue)", ctxt);

         g_autofree char *binary = virXPathString("string(./binary/@path)", ctxt);

+        g_autofree char *thread_pool_size = virXPathString("string(./binary/thread_pool/@size)", ctxt);

         g_autofree char *xattr = virXPathString("string(./binary/@xattr)", ctxt);

         g_autofree char *cache = virXPathString("string(./binary/cache/@mode)", ctxt);

         g_autofree char *sandbox = virXPathString("string(./binary/sandbox/@mode)", ctxt);

@@ -9883,6 +9886,14 @@ virDomainFSDefParseXML(virDomainXMLOption *xmlopt,

             goto error;

         }

+        if (thread_pool_size &&

+            virStrToLong_i(thread_pool_size, NULL, 10, &def->thread_pool_size) < 0) {

+            virReportError(VIR_ERR_XML_ERROR,

+                           _("cannot parse thread pool size '%s' for virtiofs"),

+                           queue_size);

+            goto error;

+        }

+

         if (binary)

             def->binary = virFileSanitizePath(binary);

@@ -24205,6 +24216,10 @@ virDomainFSDefFormat(virBuffer *buf,

         }

         virXMLFormatElement(&binaryBuf, "lock", &lockAttrBuf, NULL);

+

+        if (def->thread_pool_size >= 0)

+            virBufferAsprintf(&binaryBuf, "<thread_pool size='%d'/>\n", def->thread_pool_size);

+

     }

     virDomainVirtioOptionsFormat(&driverAttrBuf, def->virtio);

diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h

index 10af94e2e4..d0d0fdc815 100644

--- a/src/conf/domain_conf.h

+++ b/src/conf/domain_conf.h

@@ -892,6 +892,7 @@ struct _virDomainFSDef {

     virTristateSwitch posix_lock;

     virTristateSwitch flock;

     virDomainFSSandboxMode sandbox;

+    int thread_pool_size;

     virDomainVirtioOptions *virtio;

     virObject *privateData;

 };

diff --git a/tests/qemuxml2argvdata/vhost-user-fs-fd-memory.xml b/tests/qemuxml2argvdata/vhost-user-fs-fd-memory.xml

index abddf0870b..81de8c0dd7 100644

--- a/tests/qemuxml2argvdata/vhost-user-fs-fd-memory.xml

+++ b/tests/qemuxml2argvdata/vhost-user-fs-fd-memory.xml

@@ -32,6 +32,7 @@

         <cache mode='always'/>

         <sandbox mode='chroot'/>

         <lock posix='off' flock='off'/>

+        <thread_pool size='16'/>

       </binary>

       <source dir='/path'/>

       <target dir='mount_tag'/>

-- 

2.35.1