From: Stefan Hajnoczi <stefanha@redhat.com> To: Mike Christie <michael.christie@oracle.com> Cc: target-devel@vger.kernel.org, linux-scsi@vger.kernel.org, pbonzini@redhat.com, jasowang@redhat.com, mst@redhat.com, sgarzare@redhat.com, virtualization@lists.linux-foundation.org Subject: Re: [PATCH 3/9] vhost: modify internal functions to take a vhost_worker Date: Thu, 3 Jun 2021 11:45:01 +0100 [thread overview] Message-ID: <YLiyrRdeD6vQ2VXc@stefanha-x1.localdomain> (raw) In-Reply-To: <20210525180600.6349-4-michael.christie@oracle.com> [-- Attachment #1: Type: text/plain, Size: 2311 bytes --] On Tue, May 25, 2021 at 01:05:54PM -0500, Mike Christie wrote: > -void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work) > +static void vhost_work_queue_on(struct vhost_work *work, > + struct vhost_worker *worker) > { > - if (!dev->worker) > - return; > - > if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) { > /* We can only add the work to the list after we're > * sure it was not in the list. > * test_and_set_bit() implies a memory barrier. > */ > - llist_add(&work->node, &dev->worker->work_list); > - wake_up_process(dev->worker->task); > + llist_add(&work->node, &worker->work_list); > + wake_up_process(worker->task); > } > } > + > +void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work) When should this function still be used? A doc comment contrasting it to vhost_work_queue_on() would be helpful. I would expect callers to switch to that instead of queuing work on dev->workers[0]. > /* A lockless hint for busy polling code to exit the loop */ > bool vhost_has_work(struct vhost_dev *dev) > { > - return dev->worker && !llist_empty(&dev->worker->work_list); > + int i; > + > + for (i = 0; i < dev->num_workers; i++) { > + if (!llist_empty(&dev->workers[i]->work_list)) > + return true; > + } > + > + return false; > } > EXPORT_SYMBOL_GPL(vhost_has_work); It's probably not necessary to poll all workers: drivers/vhost/net.c calls vhost_has_work() to busy poll a specific virtqueue. If the vq:worker mapping is 1:1 or N:1 then vhost_has_work() should be extended to include the struct vhost_virtqueue so we can poll just that vq worker's work_list. > /* Caller must have device mutex */ > static int vhost_worker_try_create_def(struct vhost_dev *dev) > { > - if (!dev->use_worker || dev->worker) > + struct vhost_worker *worker; > + > + if (!dev->use_worker || dev->workers) > return 0; > > - return vhost_worker_create(dev); > + dev->workers = kcalloc(1, sizeof(struct vhost_worker *), GFP_KERNEL); GFP_KERNEL_ACCOUNT so that vhost memory associated with a process (the one that invoked the ioctl) is accounted? This may get trickier if the workers are shared between processes. The same applies for struct vhost_worker in vhost_worker_create(). [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 488 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Stefan Hajnoczi <stefanha@redhat.com> To: Mike Christie <michael.christie@oracle.com> Cc: linux-scsi@vger.kernel.org, mst@redhat.com, virtualization@lists.linux-foundation.org, target-devel@vger.kernel.org, pbonzini@redhat.com Subject: Re: [PATCH 3/9] vhost: modify internal functions to take a vhost_worker Date: Thu, 3 Jun 2021 11:45:01 +0100 [thread overview] Message-ID: <YLiyrRdeD6vQ2VXc@stefanha-x1.localdomain> (raw) In-Reply-To: <20210525180600.6349-4-michael.christie@oracle.com> [-- Attachment #1.1: Type: text/plain, Size: 2311 bytes --] On Tue, May 25, 2021 at 01:05:54PM -0500, Mike Christie wrote: > -void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work) > +static void vhost_work_queue_on(struct vhost_work *work, > + struct vhost_worker *worker) > { > - if (!dev->worker) > - return; > - > if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) { > /* We can only add the work to the list after we're > * sure it was not in the list. > * test_and_set_bit() implies a memory barrier. > */ > - llist_add(&work->node, &dev->worker->work_list); > - wake_up_process(dev->worker->task); > + llist_add(&work->node, &worker->work_list); > + wake_up_process(worker->task); > } > } > + > +void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work) When should this function still be used? A doc comment contrasting it to vhost_work_queue_on() would be helpful. I would expect callers to switch to that instead of queuing work on dev->workers[0]. > /* A lockless hint for busy polling code to exit the loop */ > bool vhost_has_work(struct vhost_dev *dev) > { > - return dev->worker && !llist_empty(&dev->worker->work_list); > + int i; > + > + for (i = 0; i < dev->num_workers; i++) { > + if (!llist_empty(&dev->workers[i]->work_list)) > + return true; > + } > + > + return false; > } > EXPORT_SYMBOL_GPL(vhost_has_work); It's probably not necessary to poll all workers: drivers/vhost/net.c calls vhost_has_work() to busy poll a specific virtqueue. If the vq:worker mapping is 1:1 or N:1 then vhost_has_work() should be extended to include the struct vhost_virtqueue so we can poll just that vq worker's work_list. > /* Caller must have device mutex */ > static int vhost_worker_try_create_def(struct vhost_dev *dev) > { > - if (!dev->use_worker || dev->worker) > + struct vhost_worker *worker; > + > + if (!dev->use_worker || dev->workers) > return 0; > > - return vhost_worker_create(dev); > + dev->workers = kcalloc(1, sizeof(struct vhost_worker *), GFP_KERNEL); GFP_KERNEL_ACCOUNT so that vhost memory associated with a process (the one that invoked the ioctl) is accounted? This may get trickier if the workers are shared between processes. The same applies for struct vhost_worker in vhost_worker_create(). [-- Attachment #1.2: signature.asc --] [-- Type: application/pgp-signature, Size: 488 bytes --] [-- Attachment #2: Type: text/plain, Size: 183 bytes --] _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
next prev parent reply other threads:[~2021-06-03 10:45 UTC|newest] Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-25 18:05 vhost: multiple worker support Mike Christie 2021-05-25 18:05 ` Mike Christie 2021-05-25 18:05 ` [PATCH 1/9] vhost: move worker thread fields to new struct Mike Christie 2021-05-25 18:05 ` Mike Christie 2021-06-03 10:16 ` Stefan Hajnoczi 2021-06-03 10:16 ` Stefan Hajnoczi 2021-05-25 18:05 ` [PATCH 2/9] vhost: move vhost worker creation to kick setup Mike Christie 2021-05-25 18:05 ` Mike Christie 2021-06-03 10:28 ` Stefan Hajnoczi 2021-06-03 10:28 ` Stefan Hajnoczi 2021-05-25 18:05 ` [PATCH 3/9] vhost: modify internal functions to take a vhost_worker Mike Christie 2021-05-25 18:05 ` Mike Christie 2021-06-03 10:45 ` Stefan Hajnoczi [this message] 2021-06-03 10:45 ` Stefan Hajnoczi 2021-05-25 18:05 ` [PATCH 4/9] vhost: allow vhost_polls to use different vhost_workers Mike Christie 2021-05-25 18:05 ` Mike Christie 2021-06-03 13:51 ` Stefan Hajnoczi 2021-06-03 13:51 ` Stefan Hajnoczi 2021-05-25 18:05 ` [PATCH 5/9] vhost-scsi: flush IO vqs then send TMF rsp Mike Christie 2021-05-25 18:05 ` Mike Christie 2021-06-03 13:54 ` Stefan Hajnoczi 2021-06-03 13:54 ` Stefan Hajnoczi 2021-05-25 18:05 ` [PATCH 6/9] vhost-scsi: make SCSI cmd completion per vq Mike Christie 2021-05-25 18:05 ` Mike Christie 2021-06-03 13:57 ` Stefan Hajnoczi 2021-06-03 13:57 ` Stefan Hajnoczi 2021-05-25 18:05 ` [PATCH 7/9] vhost: allow userspace to create workers Mike Christie 2021-05-25 18:05 ` Mike Christie 2021-06-03 14:30 ` Stefan Hajnoczi 2021-06-03 14:30 ` Stefan Hajnoczi 2021-06-05 23:53 ` michael.christie 2021-06-05 23:53 ` michael.christie 2021-06-07 15:19 ` Stefan Hajnoczi 2021-06-07 15:19 ` Stefan Hajnoczi 2021-06-09 21:03 ` Mike Christie 2021-06-09 21:03 ` Mike Christie 2021-06-10 8:06 ` Stefan Hajnoczi 2021-06-10 8:06 ` Stefan Hajnoczi 2021-06-18 2:49 ` Mike Christie 2021-06-18 2:49 ` Mike Christie 2021-06-21 13:41 ` Stefan Hajnoczi 2021-06-21 13:41 ` Stefan Hajnoczi 2021-05-25 18:05 ` [PATCH 8/9] vhost: add vhost_dev pointer to vhost_work Mike Christie 2021-05-25 18:05 ` Mike Christie 2021-06-03 14:31 ` Stefan Hajnoczi 2021-06-03 14:31 ` Stefan Hajnoczi 2021-05-25 18:06 ` [PATCH 9/9] vhost: support sharing workers across devs Mike Christie 2021-05-25 18:06 ` Mike Christie 2021-06-03 14:32 ` Stefan Hajnoczi 2021-06-03 14:32 ` Stefan Hajnoczi 2021-06-07 2:18 ` Jason Wang 2021-06-07 2:18 ` Jason Wang 2021-06-03 10:13 ` vhost: multiple worker support Stefan Hajnoczi 2021-06-03 10:13 ` Stefan Hajnoczi 2021-06-03 18:45 ` Mike Christie 2021-06-03 18:45 ` Mike Christie 2021-06-03 14:37 ` Stefan Hajnoczi 2021-06-03 14:37 ` Stefan Hajnoczi 2021-06-03 22:16 ` Mike Christie 2021-06-03 22:16 ` Mike Christie 2021-06-05 22:40 ` michael.christie 2021-06-05 22:40 ` michael.christie 2021-06-07 15:23 ` Stefan Hajnoczi 2021-06-07 15:23 ` Stefan Hajnoczi
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