here some tips I use to improve librbd performance && qemu:
- disabling cephx auth
- disable debug_ms : (I'm jumping from 30k iops to 45k iops, with 4k randread)
[global]
debug ms = 0/0
- compile qemu with jemalloc (--enable-jemalloc)
https://lists.gnu.org/archive/html/qemu-devel/2015-06/msg05265.html
- Mail original -
De: "Jason Dillaman"
À: "Bill WONG"
Cc: "aderumier" , "ceph-users"
Envoyé: Mardi 1 Novembre 2016 02:06:22
Objet: Re: [ceph-users] RBD Block performance vs rbd mount as filesystem
For better or worse, I can repeat your "ioping" findings against a
qcow2 image hosted on a krbd-backed volume. The "bad" news is that it
actually isn't even sending any data to the OSDs -- which is why your
latency is shockingly low. When performing a "dd ... oflag=dsync"
against the krbd-backed qcow2 image, I can see lots of IO being
coalesced from 4K writes into larger writes, which is artificially
inflating the stats.
On Mon, Oct 31, 2016 at 11:08 AM, Bill WONG wrote:
> Hi Jason,
>
> it looks the situation is the same, no difference. my ceph.conf is below,
> any comments or improvement required?
> ---
> [global]
> fsid = 106a12b0-5ed0-4a71-b6aa-68a09088ec33
> mon_initial_members = ceph-mon1, ceph-mon2, ceph-mon3
> mon_host = 192.168.8.11,192.168.8.12,192.168.8.13
> auth_cluster_required = cephx
> auth_service_required = cephx
> auth_client_required = cephx
> filestore_xattr_use_omap = true
> osd pool default size = 3
> osd pool default min size = 1
> osd pool default pg num = 4096
> osd pool default pgp num = 4096
> osd_crush_chooseleaf_type = 1
> mon_pg_warn_max_per_osd = 0
> max_open_files = 131072
>
> [mon]
> mon_data = /var/lib/ceph/mon/ceph-$id
>
> mon clock drift allowed = 2
> mon clock drift warn backoff = 30
>
> [osd]
> osd_data = /var/lib/ceph/osd/ceph-$id
> osd_journal_size = 2
> osd_mkfs_type = xfs
> osd_mkfs_options_xfs = -f
> filestore_xattr_use_omap = true
> filestore_min_sync_interval = 10
> filestore_max_sync_interval = 15
> filestore_queue_max_ops = 25000
> filestore_queue_max_bytes = 10485760
> filestore_queue_committing_max_ops = 5000
> filestore_queue_committing_max_bytes = 1048576
> journal_max_write_bytes = 1073714824
> journal_max_write_entries = 1
> journal_queue_max_ops = 5
> journal_queue_max_bytes = 1048576
> osd_max_write_size = 512
> osd_client_message_size_cap = 2147483648
> osd_deep_scrub_stride = 131072
> osd_op_threads = 8
> osd_disk_threads = 4
> osd_map_cache_size = 1024
> osd_map_cache_bl_size = 128
> osd_mount_options_xfs = "rw,noexec,nodev,noatime,nodiratime,nobarrier"
> osd_recovery_op_priority = 4
> osd_recovery_max_active = 10
> osd_max_backfills = 4
> rbd non blocking aio = false
>
> [client]
> rbd_cache = true
> rbd_cache_size = 268435456
> rbd_cache_max_dirty = 134217728
> rbd_cache_max_dirty_age = 5
> ---
>
>
>
> On Mon, Oct 31, 2016 at 9:20 PM, Jason Dillaman wrote:
>>
>> On Sun, Oct 30, 2016 at 5:40 AM, Bill WONG wrote:
>> > any ideas or comments?
>>
>> Can you set "rbd non blocking aio = false" in your ceph.conf and retry
>> librbd? This will eliminate at least one context switch on the read IO
>> path -- which result in increased latency under extremely low queue
>> depths.
>>
>> --
>> Jason
>
>
--
Jason
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