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Re: [Qemu-devel] [PATCH v3 08/29] raw: Probe required direct I/O alignme
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH v3 08/29] raw: Probe required direct I/O alignment |
Date: |
Tue, 21 Jan 2014 14:29:50 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Am 21.01.2014 um 14:03 hat Benoît Canet geschrieben:
> Le Friday 17 Jan 2014 à 15:14:58 (+0100), Kevin Wolf a écrit :
> > From: Paolo Bonzini <address@hidden>
> >
> > Add a bs->request_alignment field that contains the required
> > offset/length alignment for I/O requests and fill it in the raw block
> > drivers. Use ioctls if possible, else see what alignment it takes for
> > O_DIRECT to succeed.
> >
> > While at it, also expose the memory alignment requirements, which may be
> > (and in practice are) different from the disk alignment requirements.
> >
> > Signed-off-by: Paolo Bonzini <address@hidden>
> > Signed-off-by: Kevin Wolf <address@hidden>
> > Reviewed-by: Max Reitz <address@hidden>
> > ---
> > block.c | 3 ++
> > block/raw-posix.c | 102
> > ++++++++++++++++++++++++++++++++++++++--------
> > block/raw-win32.c | 41 +++++++++++++++++++
> > include/block/block_int.h | 3 ++
> > 4 files changed, 132 insertions(+), 17 deletions(-)
> >
> > diff --git a/block.c b/block.c
> > index b738abe..25ae896 100644
> > --- a/block.c
> > +++ b/block.c
> > @@ -813,6 +813,7 @@ static int bdrv_open_common(BlockDriverState *bs,
> > BlockDriverState *file,
> >
> > bs->open_flags = flags;
> > bs->guest_block_size = 512;
> > + bs->request_alignment = 512;
> > bs->zero_beyond_eof = true;
> > open_flags = bdrv_open_flags(bs, flags);
> > bs->read_only = !(open_flags & BDRV_O_RDWR);
> > @@ -881,6 +882,8 @@ static int bdrv_open_common(BlockDriverState *bs,
> > BlockDriverState *file,
> > }
> >
> > bdrv_refresh_limits(bs);
> > + assert(bdrv_opt_mem_align(bs) != 0);
> > + assert(bs->request_alignment != 0);
> >
> > #ifndef _WIN32
> > if (bs->is_temporary) {
> > diff --git a/block/raw-posix.c b/block/raw-posix.c
> > index 0676037..126a634 100644
> > --- a/block/raw-posix.c
> > +++ b/block/raw-posix.c
> > @@ -127,6 +127,8 @@ typedef struct BDRVRawState {
> > int fd;
> > int type;
> > int open_flags;
> > + size_t buf_align;
> > +
> > #if defined(__linux__)
> > /* linux floppy specific */
> > int64_t fd_open_time;
> > @@ -213,6 +215,76 @@ static int raw_normalize_devicepath(const char
> > **filename)
> > }
> > #endif
> >
> > +static void raw_probe_alignment(BlockDriverState *bs)
> > +{
> > + BDRVRawState *s = bs->opaque;
> > + char *buf;
> > + unsigned int sector_size;
> > +
> > + /* For /dev/sg devices the alignment is not really used.
> > + With buffered I/O, we don't have any restrictions. */
> > + if (bs->sg || !(s->open_flags & O_DIRECT)) {
> > + bs->request_alignment = 1;
> > + s->buf_align = 1;
> > + return;
> > + }
> > +
> > + /* Try a few ioctls to get the right size */
> > + bs->request_alignment = 0;
> > + s->buf_align = 0;
> > +
> > +#ifdef BLKSSZGET
> > + if (ioctl(s->fd, BLKSSZGET, §or_size) >= 0) {
> > + bs->request_alignment = sector_size;
> > + }
> > +#endif
> > +#ifdef DKIOCGETBLOCKSIZE
> > + if (ioctl(s->fd, DKIOCGETBLOCKSIZE, §or_size) >= 0) {
> > + bs->request_alignment = sector_size;
> > + }
> > +#endif
> > +#ifdef DIOCGSECTORSIZE
> > + if (ioctl(s->fd, DIOCGSECTORSIZE, §or_size) >= 0) {
> > + bs->request_alignment = sector_size;
> > + }
> > +#endif
> > +#ifdef CONFIG_XFS
> > + if (s->is_xfs) {
> > + struct dioattr da;
> > + if (xfsctl(NULL, s->fd, XFS_IOC_DIOINFO, &da) >= 0) {
> > + bs->request_alignment = da.d_miniosz;
> > + /* The kernel returns wrong information for d_mem */
> > + /* s->buf_align = da.d_mem; */
> > + }
> > + }
> > +#endif
> > +
> > + /* If we could not get the sizes so far, we can only guess them */
> > + if (!s->buf_align) {
> > + size_t align;
> > + buf = qemu_memalign(MAX_BLOCKSIZE, 2 * MAX_BLOCKSIZE);
> > + for (align = 512; align <= MAX_BLOCKSIZE; align <<= 1) {
> > + if (pread(s->fd, buf + align, MAX_BLOCKSIZE, 0) >= 0) {
> > + s->buf_align = align;
> > + break;
> > + }
> > + }
> > + qemu_vfree(buf);
> > + }
> > +
> > + if (!bs->request_alignment) {
> > + size_t align;
> > + buf = qemu_memalign(s->buf_align, MAX_BLOCKSIZE);
> > + for (align = 512; align <= MAX_BLOCKSIZE; align <<= 1) {
> > + if (pread(s->fd, buf, align, 0) >= 0) {
> > + bs->request_alignment = align;
> > + break;
> > + }
> > + }
> > + qemu_vfree(buf);
> > + }
> > +}
> > +
> > static void raw_parse_flags(int bdrv_flags, int *open_flags)
> > {
> > assert(open_flags != NULL);
> > @@ -463,7 +535,6 @@ static int raw_reopen_prepare(BDRVReopenState *state,
> > return ret;
> > }
> >
> > -
> > static void raw_reopen_commit(BDRVReopenState *state)
> > {
> > BDRVRawReopenState *raw_s = state->opaque;
> > @@ -499,23 +570,15 @@ static void raw_reopen_abort(BDRVReopenState *state)
> > state->opaque = NULL;
> > }
> >
> > +static int raw_refresh_limits(BlockDriverState *bs)
> > +{
> > + BDRVRawState *s = bs->opaque;
> >
> > -/* XXX: use host sector size if necessary with:
> > -#ifdef DIOCGSECTORSIZE
> > - {
> > - unsigned int sectorsize = 512;
> > - if (!ioctl(fd, DIOCGSECTORSIZE, §orsize) &&
> > - sectorsize > bufsize)
> > - bufsize = sectorsize;
> > - }
> > -#endif
> > -#ifdef CONFIG_COCOA
> > - uint32_t blockSize = 512;
> > - if ( !ioctl( fd, DKIOCGETBLOCKSIZE, &blockSize ) && blockSize >
> > bufsize) {
> > - bufsize = blockSize;
> > - }
> > -#endif
> > -*/
> > + raw_probe_alignment(bs);
> > + bs->bl.opt_mem_alignment = s->buf_align;
> > +
> > + return 0;
> > +}
> >
> > static ssize_t handle_aiocb_ioctl(RawPosixAIOData *aiocb)
> > {
> > @@ -1363,6 +1426,7 @@ static BlockDriver bdrv_file = {
> > .bdrv_aio_writev = raw_aio_writev,
> > .bdrv_aio_flush = raw_aio_flush,
> > .bdrv_aio_discard = raw_aio_discard,
> > + .bdrv_refresh_limits = raw_refresh_limits,
> >
> > .bdrv_truncate = raw_truncate,
> > .bdrv_getlength = raw_getlength,
> > @@ -1740,6 +1804,7 @@ static BlockDriver bdrv_host_device = {
> > .bdrv_aio_writev = raw_aio_writev,
> > .bdrv_aio_flush = raw_aio_flush,
> > .bdrv_aio_discard = hdev_aio_discard,
> > + .bdrv_refresh_limits = raw_refresh_limits,
> >
> > .bdrv_truncate = raw_truncate,
> > .bdrv_getlength = raw_getlength,
> > @@ -1871,6 +1936,7 @@ static BlockDriver bdrv_host_floppy = {
> > .bdrv_aio_readv = raw_aio_readv,
> > .bdrv_aio_writev = raw_aio_writev,
> > .bdrv_aio_flush = raw_aio_flush,
> > + .bdrv_refresh_limits = raw_refresh_limits,
> >
> > .bdrv_truncate = raw_truncate,
> > .bdrv_getlength = raw_getlength,
> > @@ -1981,6 +2047,7 @@ static BlockDriver bdrv_host_cdrom = {
> > .bdrv_aio_readv = raw_aio_readv,
> > .bdrv_aio_writev = raw_aio_writev,
> > .bdrv_aio_flush = raw_aio_flush,
> > + .bdrv_refresh_limits = raw_refresh_limits,
> >
> > .bdrv_truncate = raw_truncate,
> > .bdrv_getlength = raw_getlength,
> > @@ -2110,6 +2177,7 @@ static BlockDriver bdrv_host_cdrom = {
> > .bdrv_aio_readv = raw_aio_readv,
> > .bdrv_aio_writev = raw_aio_writev,
> > .bdrv_aio_flush = raw_aio_flush,
> > + .bdrv_refresh_limits = raw_refresh_limits,
> >
> > .bdrv_truncate = raw_truncate,
> > .bdrv_getlength = raw_getlength,
> > diff --git a/block/raw-win32.c b/block/raw-win32.c
> > index ce314fd..beb7f23 100644
> > --- a/block/raw-win32.c
> > +++ b/block/raw-win32.c
> > @@ -202,6 +202,35 @@ static int set_sparse(int fd)
> > NULL, 0, NULL, 0, &returned, NULL);
> > }
> >
> > +static void raw_probe_alignment(BlockDriverState *bs)
> > +{
> > + BDRVRawState *s = bs->opaque;
> > + DWORD sectorsPerCluster, freeClusters, totalClusters, count;
> > + DISK_GEOMETRY_EX dg;
> > + BOOL status;
> > +
> > + if (s->type == FTYPE_CD) {
> > + bs->request_alignment = 2048;
> > + return;
> > + }
> > + if (s->type == FTYPE_HARDDISK) {
> > + status = DeviceIoControl(s->hfile,
> > IOCTL_DISK_GET_DRIVE_GEOMETRY_EX,
> > + NULL, 0, &dg, sizeof(dg), &count, NULL);
> > + if (status != 0) {
> > + bs->request_alignment = dg.Geometry.BytesPerSector;
> > + return;
> > + }
> > + /* try GetDiskFreeSpace too */
> > + }
> > +
> > + if (s->drive_path[0]) {
> > + GetDiskFreeSpace(s->drive_path, §orsPerCluster,
> > + &dg.Geometry.BytesPerSector,
> > + &freeClusters, &totalClusters);
> > + bs->request_alignment = dg.Geometry.BytesPerSector;
> > + }
> > +}
> > +
> > static void raw_parse_flags(int flags, int *access_flags, DWORD
> > *overlapped)
> > {
> > assert(access_flags != NULL);
> > @@ -269,6 +298,17 @@ static int raw_open(BlockDriverState *bs, QDict
> > *options, int flags,
> > }
> > }
> >
> > + if (filename[0] && filename[1] == ':') {
> > + snprintf(s->drive_path, sizeof(s->drive_path), "%c:\\",
> > filename[0]);
> > + } else if (filename[0] == '\\' && filename[1] == '\\') {
> > + s->drive_path[0] = 0;
> > + } else {
> > + /* Relative path. */
> > + char buf[MAX_PATH];
> > + GetCurrentDirectory(MAX_PATH, buf);
> > + snprintf(s->drive_path, sizeof(s->drive_path), "%c:\\", buf[0]);
> > + }
> > +
> This is not really alignment related.
> Does this really belong to this patch ?
raw_probe_alignment() needs the path, so s->drive_path must now be
initialised for all images. Without this change it is only set in
hdev_open(), i.e. for win32 host_device backends.
Kevin
- [Qemu-devel] [PATCH v3 02/29] block: Inherit opt_transfer_length, (continued)
- [Qemu-devel] [PATCH v3 02/29] block: Inherit opt_transfer_length, Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 03/29] block: Update BlockLimits when they might have changed, Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 04/29] qemu_memalign: Allow small alignments, Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 05/29] block: Detect unaligned length in bdrv_qiov_is_aligned(), Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 06/29] block: Don't use guest sector size for qemu_blockalign(), Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 08/29] raw: Probe required direct I/O alignment, Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 09/29] block: Introduce bdrv_aligned_preadv(), Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 10/29] block: Introduce bdrv_co_do_preadv(), Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 07/29] block: rename buffer_alignment to guest_block_size, Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 11/29] block: Introduce bdrv_aligned_pwritev(), Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 12/29] block: write: Handle COR dependency after I/O throttling, Kevin Wolf, 2014/01/17