On Fri, 21 Feb 2014, Ilya Dryomov wrote:
> This is primarily for rbd's benefit and is supposed to combat
> fragmentation:
>
> "... knowing that rbd images have a 4m size, librbd can pass a hint
> that will let the osd do the xfs allocation size ioctl on new files so
> that they are allocated in 1m or 4m chunks. We've seen cases where
> users with rbd workloads have very high levels of fragmentation in xfs
> and this would mitigate that and probably have a pretty nice
> performance benefit."
>
> SETALLOCHINT is considered advisory, so our backwards compatibility
> mechanism here is to set FAILOK flag for all SETALLOCHINT ops.
>
> Signed-off-by: Ilya Dryomov <ilya.dryomov@xxxxxxxxxxx>
> ---
> include/linux/ceph/osd_client.h | 9 +++++++++
> include/linux/ceph/rados.h | 8 ++++++++
> net/ceph/osd_client.c | 30 ++++++++++++++++++++++++++++++
> 3 files changed, 47 insertions(+)
>
> diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
> index e94f5da251d6..6bfcb0eca8ab 100644
> --- a/include/linux/ceph/osd_client.h
> +++ b/include/linux/ceph/osd_client.h
> @@ -103,6 +103,11 @@ struct ceph_osd_req_op {
> u32 timeout;
> __u8 flag;
> } watch;
> + struct {
> + u64 expected_size;
> + u64 expected_write_size;
> + __u8 expected_size_probability;
> + } hint;
s/hint/alloc_hint/ ?
> };
> };
>
> @@ -294,6 +299,10 @@ extern void osd_req_op_cls_init(struct ceph_osd_request *osd_req,
> extern void osd_req_op_watch_init(struct ceph_osd_request *osd_req,
> unsigned int which, u16 opcode,
> u64 cookie, u64 version, int flag);
> +extern void osd_req_op_hint_init(struct ceph_osd_request *osd_req,
> + unsigned int which, u16 opcode,
> + u64 expected_size, u64 expected_write_size,
> + u8 expected_size_probability);
>
> extern struct ceph_osd_request *ceph_osdc_alloc_request(struct ceph_osd_client *osdc,
> struct ceph_snap_context *snapc,
> diff --git a/include/linux/ceph/rados.h b/include/linux/ceph/rados.h
> index 8f9bf4570215..b8e2dd11f186 100644
> --- a/include/linux/ceph/rados.h
> +++ b/include/linux/ceph/rados.h
> @@ -227,6 +227,9 @@ enum {
> CEPH_OSD_OP_OMAPRMKEYS = CEPH_OSD_OP_MODE_WR | CEPH_OSD_OP_TYPE_DATA | 24,
> CEPH_OSD_OP_OMAP_CMP = CEPH_OSD_OP_MODE_RD | CEPH_OSD_OP_TYPE_DATA | 25,
>
> + /* hints */
> + CEPH_OSD_OP_SETALLOCHINT = CEPH_OSD_OP_MODE_WR | CEPH_OSD_OP_TYPE_DATA | 35,
> +
> /** multi **/
> CEPH_OSD_OP_CLONERANGE = CEPH_OSD_OP_MODE_WR | CEPH_OSD_OP_TYPE_MULTI | 1,
> CEPH_OSD_OP_ASSERT_SRC_VERSION = CEPH_OSD_OP_MODE_RD | CEPH_OSD_OP_TYPE_MULTI | 2,
> @@ -416,6 +419,11 @@ struct ceph_osd_op {
> __le64 offset, length;
> __le64 src_offset;
> } __attribute__ ((packed)) clonerange;
> + struct {
> + __le64 expected_size;
> + __le64 expected_write_size;
> + __u8 expected_size_probability;
> + } __attribute__ ((packed)) hint;
s/hint/alloc_hint/, I think. Just made the same comment on the user space
side.
> };
> __le32 payload_len;
> } __attribute__ ((packed));
> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> index 5d7fd0b8c1c8..4090f6e8db3a 100644
> --- a/net/ceph/osd_client.c
> +++ b/net/ceph/osd_client.c
> @@ -436,6 +436,7 @@ static bool osd_req_opcode_valid(u16 opcode)
> case CEPH_OSD_OP_OMAPCLEAR:
> case CEPH_OSD_OP_OMAPRMKEYS:
> case CEPH_OSD_OP_OMAP_CMP:
> + case CEPH_OSD_OP_SETALLOCHINT:
> case CEPH_OSD_OP_CLONERANGE:
> case CEPH_OSD_OP_ASSERT_SRC_VERSION:
> case CEPH_OSD_OP_SRC_CMPXATTR:
> @@ -591,6 +592,28 @@ void osd_req_op_watch_init(struct ceph_osd_request *osd_req,
> }
> EXPORT_SYMBOL(osd_req_op_watch_init);
>
> +void osd_req_op_hint_init(struct ceph_osd_request *osd_req,
> + unsigned int which, u16 opcode,
> + u64 expected_size, u64 expected_write_size,
> + u8 expected_size_probability)
> +{
> + struct ceph_osd_req_op *op = _osd_req_op_init(osd_req, which, opcode);
> +
> + BUG_ON(opcode != CEPH_OSD_OP_SETALLOCHINT);
I would just drop the opcode argument all together. And
s/hint/alloc_hint/ in the function name... I wouldn't expect that any
other type of hint would have these same arguments.
> +
> + op->hint.expected_size = expected_size;
> + op->hint.expected_write_size = expected_write_size;
> + op->hint.expected_size_probability = expected_size_probability;
> +
> + /*
> + * CEPH_OSD_OP_SETALLOCHINT op is advisory and therefore deemed
> + * not worth a feature bit. Set FAILOK per-op flag to make
> + * sure older osds don't trip over an unsupported opcode.
> + */
> + op->flags |= CEPH_OSD_OP_FLAG_FAILOK;
> +}
> +EXPORT_SYMBOL(osd_req_op_hint_init);
> +
> static void ceph_osdc_msg_data_add(struct ceph_msg *msg,
> struct ceph_osd_data *osd_data)
> {
> @@ -681,6 +704,13 @@ static u64 osd_req_encode_op(struct ceph_osd_request *req,
> dst->watch.ver = cpu_to_le64(src->watch.ver);
> dst->watch.flag = src->watch.flag;
> break;
> + case CEPH_OSD_OP_SETALLOCHINT:
> + dst->hint.expected_size = cpu_to_le64(src->hint.expected_size);
> + dst->hint.expected_write_size =
> + cpu_to_le64(src->hint.expected_write_size);
> + dst->hint.expected_size_probability =
> + src->hint.expected_size_probability;
> + break;
> default:
> pr_err("unsupported osd opcode %s\n",
> ceph_osd_op_name(src->op));
> --
> 1.7.10.4
>
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