On 12/15/2011 08:15 PM, Sasha Levin wrote:
> When using AIO, submit all requests which exists in the vring in a single
> io_submit instead of one io_submit for each descriptor.
>
> Benchmarks:
>
> Short version: 15%+ increase in IOPS, small increase in BW.
>
> Read IOPS:
> Before:
> vda: ios=291792/0, merge=0/0, ticks=35229/0, in_queue=31025, util=61.30%
I guess you are reading the wrong IOPS number, the 'ios' is the number
of ios performed by all groups, not the IOPS result. Find the 'iops' ;-)
So, Here is the number without/with this patch.
(seq-read, seq-write, rand-read, rand-write)
Before:
read : io=98304KB, bw=63015KB/s, iops=15753, runt= 1560msec
write: io=98304KB, bw=56823KB/s, iops=14205, runt= 1730msec
read : io=98304KB, bw=62139KB/s, iops=15534, runt= 1582msec
write: io=98304KB, bw=53836KB/s, iops=13458, runt= 1826msec
After:
read : io=98304KB, bw=63096KB/s, iops=15774, runt= 1558msec
write: io=98304KB, bw=55823KB/s, iops=13955, runt= 1761msec
read : io=98304KB, bw=59148KB/s, iops=14787, runt= 1662msec
write: io=98304KB, bw=55072KB/s, iops=13768, runt= 1785msec
Submit more io requests in one time is not supposed to increase the iops
or bw so dramatically.
I even tried to submit all read/write ops in one io_submit which still
ends up with very little iops or bw improvement.
>
> After:
> vda: ios=333114/0, merge=0/0, ticks=47983/0, in_queue=46630, util=62.22%
>
> Write IOPS:
> Before:
> vda: ios=0/271716, merge=0/0, ticks=0/33367, in_queue=26531, util=59.96%
>
> After:
> vda: ios=0/327485, merge=0/0, ticks=0/23789, in_queue=22475, util=55.74%
>
> Read BW:
> Before:
> READ: io=7526.0MB, aggrb=1246.3MB/s, minb=1275.1MB/s, maxb=1275.1MB/s, mint=6040msec, maxt=6040msec
> After:
> READ: io=7526.0MB, aggrb=1315.5MB/s, minb=1346.7MB/s, maxb=1346.7MB/s, mint=5723msec, maxt=5723msec
>
> Write BW:
> Before:
> WRITE: io=7526.0MB, aggrb=1110.2MB/s, minb=1136.9MB/s, maxb=1136.9MB/s, mint=6779msec, maxt=6779msec
>
> After:
> WRITE: io=7526.0MB, aggrb=1113.5MB/s, minb=1140.3MB/s, maxb=1140.3MB/s, mint=6759msec, maxt=6759msec
>
> Signed-off-by: Sasha Levin <levinsasha928@xxxxxxxxx>
> ---
> tools/kvm/disk/core.c | 2 -
> tools/kvm/disk/raw.c | 38 +++++++++++++++++++++++++++++------
> tools/kvm/include/kvm/disk-image.h | 8 +++++-
> tools/kvm/util/read-write.c | 8 +-----
> tools/kvm/virtio/blk.c | 3 ++
> 5 files changed, 42 insertions(+), 17 deletions(-)
>
> diff --git a/tools/kvm/disk/core.c b/tools/kvm/disk/core.c
> index 4915efd..b18014e 100644
> --- a/tools/kvm/disk/core.c
> +++ b/tools/kvm/disk/core.c
> @@ -5,8 +5,6 @@
> #include <sys/eventfd.h>
> #include <sys/poll.h>
>
> -#define AIO_MAX 32
> -
> int debug_iodelay;
>
> #ifdef CONFIG_HAS_AIO
> diff --git a/tools/kvm/disk/raw.c b/tools/kvm/disk/raw.c
> index caa023c..1162fb7 100644
> --- a/tools/kvm/disk/raw.c
> +++ b/tools/kvm/disk/raw.c
> @@ -10,9 +10,9 @@ ssize_t raw_image__read_sector(struct disk_image *disk, u64 sector, const struct
> u64 offset = sector << SECTOR_SHIFT;
>
> #ifdef CONFIG_HAS_AIO
> - struct iocb iocb;
> + struct iocb *iocb = &disk->iocb[disk->count++];
>
> - return aio_preadv(disk->ctx, &iocb, disk->fd, iov, iovcount, offset,
> + return aio_preadv(disk->ctx, iocb, disk->fd, iov, iovcount, offset,
> disk->evt, param);
> #else
> return preadv_in_full(disk->fd, iov, iovcount, offset);
> @@ -25,9 +25,9 @@ ssize_t raw_image__write_sector(struct disk_image *disk, u64 sector, const struc
> u64 offset = sector << SECTOR_SHIFT;
>
> #ifdef CONFIG_HAS_AIO
> - struct iocb iocb;
> + struct iocb *iocb = &disk->iocb[disk->count++];
>
> - return aio_pwritev(disk->ctx, &iocb, disk->fd, iov, iovcount, offset,
> + return aio_pwritev(disk->ctx, iocb, disk->fd, iov, iovcount, offset,
> disk->evt, param);
> #else
> return pwritev_in_full(disk->fd, iov, iovcount, offset);
> @@ -79,19 +79,33 @@ int raw_image__close(struct disk_image *disk)
>
> close(disk->evt);
>
> -#ifdef CONFIG_HAS_VIRTIO
> +#ifdef CONFIG_HAS_AIO
> io_destroy(disk->ctx);
> #endif
>
> return ret;
> }
>
> +static int raw_image__aio_submit(struct disk_image *disk)
> +{
> + int ret;
> +
> + ret = io_submit(disk->ctx, disk->count, disk->iocb_ptrs);
> + if (ret > 0)
> + disk->count = 0;
> +
> + return ret;
> +}
> +
> /*
> * multiple buffer based disk image operations
> */
> static struct disk_image_operations raw_image_regular_ops = {
> .read_sector = raw_image__read_sector,
> .write_sector = raw_image__write_sector,
> +#ifdef CONFIG_HAS_AIO
> + .submit = raw_image__aio_submit,
> +#endif
> };
>
> struct disk_image_operations ro_ops = {
> @@ -120,8 +134,13 @@ struct disk_image *raw_image__probe(int fd, struct stat *st, bool readonly)
>
> disk = disk_image__new(fd, st->st_size, &ro_ops_nowrite, DISK_IMAGE_REGULAR);
> #ifdef CONFIG_HAS_AIO
> - if (disk)
> + if (disk) {
> + int i;
> +
> disk->async = 1;
> + for (i = 0; i < AIO_MAX; i++)
> + disk->iocb_ptrs[i] = &disk->iocb[i];
> + }
> #endif
> }
>
> @@ -132,8 +151,13 @@ struct disk_image *raw_image__probe(int fd, struct stat *st, bool readonly)
> */
> disk = disk_image__new(fd, st->st_size, &raw_image_regular_ops, DISK_IMAGE_REGULAR);
> #ifdef CONFIG_HAS_AIO
> - if (disk)
> + if (disk) {
> + int i;
> +
> disk->async = 1;
> + for (i = 0; i < AIO_MAX; i++)
> + disk->iocb_ptrs[i] = &disk->iocb[i];
> + }
> #endif
> return disk;
> }
> diff --git a/tools/kvm/include/kvm/disk-image.h b/tools/kvm/include/kvm/disk-image.h
> index 56c08da..6eba950 100644
> --- a/tools/kvm/include/kvm/disk-image.h
> +++ b/tools/kvm/include/kvm/disk-image.h
> @@ -20,14 +20,14 @@
>
> #define SECTOR_SHIFT 9
> #define SECTOR_SIZE (1UL << SECTOR_SHIFT)
> +#define AIO_MAX 256
> +#define MAX_DISK_IMAGES 4
>
> enum {
> DISK_IMAGE_REGULAR,
> DISK_IMAGE_MMAP,
> };
>
> -#define MAX_DISK_IMAGES 4
> -
> struct disk_image;
>
> struct disk_image_operations {
> @@ -37,6 +37,7 @@ struct disk_image_operations {
> int iovcount, void *param);
> int (*flush)(struct disk_image *disk);
> int (*close)(struct disk_image *disk);
> + int (*submit)(struct disk_image *disk);
> };
>
> struct disk_image {
> @@ -50,6 +51,9 @@ struct disk_image {
> int evt;
> #ifdef CONFIG_HAS_AIO
> io_context_t ctx;
> + struct iocb iocb[AIO_MAX];
> + struct iocb *iocb_ptrs[AIO_MAX];
> + u32 count;
> #endif
> };
>
> diff --git a/tools/kvm/util/read-write.c b/tools/kvm/util/read-write.c
> index 55473ba..4ccd554 100644
> --- a/tools/kvm/util/read-write.c
> +++ b/tools/kvm/util/read-write.c
> @@ -321,24 +321,20 @@ ssize_t pwritev_in_full(int fd, const struct iovec *iov, int iovcnt, off_t offse
> int aio_pwritev(io_context_t ctx, struct iocb *iocb, int fd, const struct iovec *iov, int iovcnt,
> off_t offset, int ev, void *param)
> {
> - struct iocb *ios[1] = { iocb };
> -
> io_prep_pwritev(iocb, fd, iov, iovcnt, offset);
> io_set_eventfd(iocb, ev);
> iocb->data = param;
>
> - return io_submit(ctx, 1, ios);
> + return 0;
> }
>
> int aio_preadv(io_context_t ctx, struct iocb *iocb, int fd, const struct iovec *iov, int iovcnt,
> off_t offset, int ev, void *param)
> {
> - struct iocb *ios[1] = { iocb };
> -
> io_prep_preadv(iocb, fd, iov, iovcnt, offset);
> io_set_eventfd(iocb, ev);
> iocb->data = param;
>
> - return io_submit(ctx, 1, ios);
> + return 0;
> }
> #endif
> \ No newline at end of file
> diff --git a/tools/kvm/virtio/blk.c b/tools/kvm/virtio/blk.c
> index d1a0197..153b11b 100644
> --- a/tools/kvm/virtio/blk.c
> +++ b/tools/kvm/virtio/blk.c
> @@ -128,6 +128,9 @@ static void virtio_blk_do_io(struct kvm *kvm, struct virt_queue *vq, struct blk_
>
> virtio_blk_do_io_request(kvm, req);
> }
> +
> + if (bdev->disk->ops->submit)
> + bdev->disk->ops->submit(bdev->disk);
> }
>
> static void set_config(struct kvm *kvm, void *dev, u8 data, u32 offset)
--
Asias He
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