[Virtio-fs] [PATCH][RFC] Support multiqueue mode by setting cpu affinity
piaojun
piaojun at huawei.com
Fri Aug 9 06:04:54 UTC 2019
Set cpu affinity for each queue in multiqueue mode to improve the iops
performance.
>From my test, the iops is increased by adding multiqueues as below,
but it has not achieved my expect yet due to some reason. So I'm
considering if we could drop some locks when operating vq as it is
binded to one vCPU. I'm very glad to have a discuss with other
developers.
Further more, I modified virtiofsd to support multiqueue which just for
testing.
Test Environment:
Guest configuration:
8 vCPU
8GB RAM
Linux 5.1 (vivek-aug-06-2019)
Host configuration:
Intel(R) Xeon(R) CPU E5-2670 0 @ 2.60GHz (8 cores x 4 threads)
32GB RAM
Linux 3.10.0
EXT4 + 4G Ramdisk
---
Single-queue:
# fio -direct=1 -time_based -iodepth=128 -rw=randwrite -ioengine=libaio -bs=4k -size=1G -numjob=8 -runtime=30 -group_reporting -name=file -filename=/mnt/virtiofs/file
file: (g=0): rw=randwrite, bs=4K-4K/4K-4K/4K-4K, ioengine=libaio, iodepth=128
...
fio-2.13
Starting 8 processes
Jobs: 8 (f=8): [w(8)] [100.0% done] [0KB/316.5MB/0KB /s] [0/81.2K/0 iops] [eta 00m:00s]
file: (groupid=0, jobs=8): err= 0: pid=5808: Fri Aug 9 20:35:22 2019
write: io=9499.9MB, bw=324251KB/s, iops=81062, runt= 30001msec
Multi-queues:
# fio -direct=1 -time_based -iodepth=128 -rw=randwrite -ioengine=libaio -bs=4k -size=1G -numjob=8 -runtime=30 -group_reporting -name=file -filename=/mnt/virtiofs/file
file: (g=0): rw=randwrite, bs=4K-4K/4K-4K/4K-4K, ioengine=libaio, iodepth=128
...
fio-2.13
Starting 8 processes
Jobs: 8 (f=8): [w(8)] [100.0% done] [0KB/444.6MB/0KB /s] [0/114K/0 iops] [eta 00m:00s]
file: (groupid=0, jobs=8): err= 0: pid=5704: Fri Aug 9 20:38:47 2019
write: io=12967MB, bw=442582KB/s, iops=110645, runt= 30001msec
---
Signed-off-by: Jun Piao <piaojun at huawei.com>
---
fs/fuse/virtio_fs.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 66 insertions(+), 2 deletions(-)
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index a04c320..7ba36fc 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -12,6 +12,7 @@
#include <linux/virtio.h>
#include <linux/virtio_fs.h>
#include <linux/delay.h>
+#include <linux/cpu.h>
#include "fuse_i.h"
/* List of virtio-fs device instances and a lock for the list */
@@ -61,6 +62,9 @@ struct virtio_fs {
void *window_kaddr;
phys_addr_t window_phys_addr;
size_t window_len;
+
+ /* Does the affinity hint is set for virtqueues? */
+ bool affinity_hint_set;
};
struct virtio_fs_forget {
@@ -378,6 +382,44 @@ static void virtio_fs_vq_done(struct virtqueue *vq)
schedule_work(&fsvq->done_work);
}
+static void virtio_fs_clean_affinity(struct virtio_fs *fs)
+{
+ int i;
+
+ if (fs->affinity_hint_set) {
+ for (i = 0; i < fs->num_queues; i++)
+ virtqueue_set_affinity(fs->vqs[i].vq, NULL);
+
+ fs->affinity_hint_set = false;
+ }
+}
+
+static void virtio_fs_set_affinity(struct virtio_fs *fs)
+{
+ int i = 0, cpu;
+
+ /*
+ * In single queue mode, we don't set the cpu affinity.
+ */
+ if (fs->num_queues == 1) {
+ virtio_fs_clean_affinity(fs);
+ fs->affinity_hint_set = false;
+ return;
+ }
+
+ /*
+ * In multiqueue mode, we let the queue to be private to one cpu
+ * by setting the affinity hint to eliminate the contention.
+ */
+ for_each_online_cpu(cpu) {
+ virtqueue_set_affinity(fs->vqs[i].vq, cpumask_of(cpu));
+ if (++i >= fs->num_queues)
+ break;
+ }
+
+ fs->affinity_hint_set = true;
+}
+
/* Initialize virtqueues */
static int virtio_fs_setup_vqs(struct virtio_device *vdev,
struct virtio_fs *fs)
@@ -440,6 +482,11 @@ static int virtio_fs_setup_vqs(struct virtio_device *vdev,
fs->vqs[i].vq = vqs[i];
fs->vqs[i].connected = true;
}
+
+ /* set affinity for vqs */
+ get_online_cpus();
+ virtio_fs_set_affinity(fs);
+ put_online_cpus();
out:
kfree(names);
kfree(callbacks);
@@ -451,6 +498,7 @@ static int virtio_fs_setup_vqs(struct virtio_device *vdev,
static void virtio_fs_cleanup_vqs(struct virtio_device *vdev,
struct virtio_fs *fs)
{
+ virtio_fs_clean_affinity(fs);
vdev->config->del_vqs(vdev);
}
@@ -954,10 +1002,22 @@ static int virtio_fs_enqueue_req(struct virtqueue *vq, struct fuse_req *req)
return ret;
}
+static unsigned virtio_fs_pick_vq_mq(struct virtio_fs *fs)
+{
+ unsigned queue_id;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ queue_id = (smp_processor_id() % fs->num_queues) + VQ_REQUEST;
+ local_irq_restore(flags);
+
+ return queue_id;
+}
+
static void virtio_fs_wake_pending_and_unlock(struct fuse_iqueue *fiq)
__releases(fiq->waitq.lock)
{
- unsigned queue_id = VQ_REQUEST; /* TODO multiqueue */
+ unsigned queue_id = VQ_REQUEST;
struct virtio_fs *fs;
struct fuse_conn *fc;
struct fuse_req *req;
@@ -972,6 +1032,8 @@ static void virtio_fs_wake_pending_and_unlock(struct fuse_iqueue *fiq)
spin_unlock(&fiq->waitq.lock);
fs = fiq->priv;
+ if (fs->num_queues > 1)
+ queue_id = virtio_fs_pick_vq_mq(fs);
fc = fs->vqs[queue_id].fud->fc;
dev_dbg(&fs->vqs[queue_id].vq->vdev->dev,
@@ -1066,9 +1128,11 @@ static int virtio_fs_fill_super(struct super_block *sb, char *opts,
err = -ENOMEM;
/* Allocate fuse_dev for hiprio and notification queues */
- for (i = 0; i < VQ_REQUEST; i++) {
+ for (i = 0; i < VQ_REQUEST + fs->num_queues; i++) {
struct virtio_fs_vq *fsvq = &fs->vqs[i];
+ if (i == VQ_REQUEST)
+ continue; /* will be allocated in fuse_fill_super_common */
fsvq->fud = fuse_dev_alloc();
if (!fsvq->fud)
goto err_free_fuse_devs;
--
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