0d976eb985
Backport a patch from upstream to fix the issue I8F6P4. Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
53 lines
1.9 KiB
Diff
53 lines
1.9 KiB
Diff
From 0e50e0bfb9bef1d26243038f0714db65a2c0e9a5 Mon Sep 17 00:00:00 2001
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From: Dongli Zhang <dongli.zhang@oracle.com>
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Date: Wed, 27 Mar 2019 18:36:35 +0800
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Subject: [PATCH] scsi: virtio_scsi: limit number of hw queues by nr_cpu_ids
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mainline inclusion
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from mainline-v5.1-rc2
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commit 1978f30a87732d4d9072a20abeded9fe17884f1b
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category: bugfix
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bugzilla: https://gitee.com/openeuler/kernel/issues/I8F6P4
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CVE: NA
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Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1978f30a87732d4d9072a20abeded9fe17884f1b
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-----------------------------------
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When tag_set->nr_maps is 1, the block layer limits the number of hw queues
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by nr_cpu_ids. No matter how many hw queues are used by virtio-scsi, as it
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has (tag_set->nr_maps == 1), it can use at most nr_cpu_ids hw queues.
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In addition, specifically for pci scenario, when the 'num_queues' specified
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by qemu is more than maxcpus, virtio-scsi would not be able to allocate
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more than maxcpus vectors in order to have a vector for each queue. As a
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result, it falls back into MSI-X with one vector for config and one shared
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for queues.
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Considering above reasons, this patch limits the number of hw queues used
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by virtio-scsi by nr_cpu_ids.
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Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
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Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
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---
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drivers/scsi/virtio_scsi.c | 1 +
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1 file changed, 1 insertion(+)
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diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
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index 8118c06f491b..ba84514b662a 100644
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--- a/drivers/scsi/virtio_scsi.c
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+++ b/drivers/scsi/virtio_scsi.c
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@@ -858,6 +858,7 @@ static int virtscsi_probe(struct virtio_device *vdev)
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/* We need to know how many queues before we allocate. */
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num_queues = virtscsi_config_get(vdev, num_queues) ? : 1;
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+ num_queues = min_t(unsigned int, nr_cpu_ids, num_queues);
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num_targets = virtscsi_config_get(vdev, max_target) + 1;
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--
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2.27.0
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