Hi Abutalib,
Given that you are on HDDs, I'd look closely at Igor's bluestore disk
allocator work, though I'm not sure how many of his changes are active
right now. Especially look closely at the min_alloc_size change.
https://github.com/ceph/ceph/pull/33365
https://github.com/ceph/ceph/pull/34588
In the past I've found that the most reliable way to figure out these
kind of issues is to do a git bisect and run the tests each time. It's
a pain and can take forever but it usually does a pretty good job of
pinpointing what's going on (even if it sometimes points out that it was
my fault due to a test error!). I'd check out the allocator work first
though.
Mark
On 8/3/20 10:29 PM, 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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