[SPDK] performance of rocksdb on blobfs

Andrey Kuzmin andrey.v.kuzmin at gmail.com
Fri May 5 00:31:38 PDT 2017


Related, are any reference RocksDB SPDK/NO_SPDK comparison results
available?

Thanks,
Andrey

On May 4, 2017 20:06, "Harris, James R" <james.r.harris at intel.com> wrote:

>
> > On May 3, 2017, at 10:04 PM, Liu, Yun1 <yun1.liu at intel.com> wrote:
> >
> >
> > I've tried db_bench in the rocksdb on blobfs, but didn't get performance
> improvement as expected.
> > Compared with NO_SPDK, insert increased 70%, readwrite increased 28%,
> but overwrite decreased 38%, randread decreased 48%.
> > (the attached pic is the detail results.)
> > Is it a normal result or is there a way that we can get a better result
> by adjusting some parameters?
> >
> > PS, here are the environment:
> > Storage: P3700, OS: CentOS 7.3, gcc: 6.3, Keys: 16B, Values: 1000B,
> Entries: 500M
>
> Hi Yun,
>
> This is not the expected result.
>
> Can you confirm a few pieces of data for me:
>
> 1) FW revision on your P3700.  Recommendation is to have FW version 1H0 or
> greater (look at last three digits in FW version).  TRIM performance
> especially is much better with more recent versions of P3700 FW and helps
> blobfs performance more than kernel/XFS performance (even with mount -o
> discard).  This would not explain randread performance differences (since
> randread does not drive any compaction which means no file deletions) but
> could affect overwrite performance.
> 2) What size of SPDK blobfs cache are you using for your tests?  Note that
> the kernel (NO_SPDK) case will use as much memory as possible for page
> cache, while SPDK blobfs will be restricted to the amount specified.  The
> run_test.sh script will override the default 4GB blobfs cache by specifying
> a larger value in the CACHE_SIZE environment variable which is specified in
> terms of MB.  So CACHE_SIZE=16384 ./run_test.sh will use 16GB of cache for
> blobfs.  Again this would likely affect performance more for the overwrite
> case, where compaction drives blobfs cache usage with flush and compaction
> operations.
> 3) Can you describe the CPU/platform you are running on?
>
> Thanks,
>
> -Jim
>
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