yeah, that's my view as well...
On 8/24/2020 10:07 PM, Mark Nelson wrote:
> Hrm, on second thought I suspect it's just more seeks on disk. Maybe
> blktrace would be more useful.
>
>
> Mark
>
>
> On 8/24/20 2:03 PM, Mark Nelson wrote:
>> Hi Igor,
>>
>>
>> If it is easily reproducible, could you run each test with gdbpmp so
>> we can observe where time is being spent?
>>
>>
>> Mark
>>
>>
>> On 8/24/20 9:26 AM, Igor Fedotov wrote:
>>>
>>> Hi All,
>>>
>>> I've just completed a small investigation on this issue.
>>>
>>> Short summary for Abutalib's benchmark scenario in my environment:
>>>
>>> - when "vstarted" cluster has WAL/DB at NVMe drive - master is ~65%
>>> faster (130 MB/s vs. 75MB/s)
>>>
>>> - in spinner-only setup (WAL/DB are at the same spinner) - octopus
>>> is 70 % faster than master ( 88MB/s vs. 52 MB/s)
>>>
>>> Looks like it is bluestore_max_blob_size_hdd set to 64K by default
>>> which causes performance drop in this case (commit sha
>>> a8733598eddf57dca86bf002653e630a7cf4db6e).
>>>
>>> Setting it back to 512K results in a better performance for master:
>>> 113 MB/s vs. 88 MB/s
>>>
>>> But I presume these numbers are tightly bound to writing 4MB chunks
>>> benchmark scenario. Different chunk size will most probably cause
>>> pretty different results. Hence reverting
>>> bluestore_max_blob_size_hdd back to 512K by default is IMO still
>>> questionable.
>>>
>>>
>>> Wondering if the above results are in-line with somebody's else
>>> ones....
>>>
>>>
>>> Thanks,
>>>
>>> Igor
>>>
>>>
>>> On 8/4/2020 6:29 AM, Abutalib Aghayev wrote:
>>>> Hi all,
>>>>
>>>> There appears to be a performance regression going from 15.2.4 to
>>>> HEAD. I first realized this when testing my patches to Ceph on an
>>>> 8-node cluster, but it is easily reproducible on *vanilla* Ceph
>>>> with vstart as well, using the following steps:
>>>>
>>>> $ git clone
https://github.com/ceph/ceph.git && cd ceph
>>>> $ ./do_cmake.sh -DCMAKE_BUILD_TYPE=RelWithDebInfo
>>>> -DWITH_MANPAGE=OFF -DWITH_BABELTRACE=OFF
>>>> -DWITH_MGR_DASHBOARD_FRONTEND=OFF && cd build && make
-j32 vstart
>>>> $ MON=1 OSD=1 MDS=0 ../src/vstart.sh --debug --new --localhost
>>>> --bluestore --bluestore-devs /dev/xxx
>>>> $ sudo ./bin/ceph osd pool create foo 32 32
>>>> $ sudo ./bin/rados bench -p foo 100 write --no-cleanup
>>>>
>>>> With the old hard drive that I have (Hitachi HUA72201), I'm getting
>>>> an average throughput of 60 MiB/s. When I switch to v15.2.4 (git
>>>> checkout v15.2.4), rebuild, and repeat the experiment, and I get an
>>>> average throughput of 90 MiB/s. I've reliably reproduced similar
>>>> difference between 15.2.4 and HEAD by building release packages and
>>>> running them on an 8-node cluster.
>>>>
>>>> Is this expected or is this a performance regression?
>>>>
>>>> Thanks!
>>>>
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