Joshua, Thanks for your note! Indeed I was using debug build b/c I am
interested in memory profile. However, when I re-built for release, it
didn't have a huge effect. However, I realized that the slowdown was
due to the fact that I was running HT with tcmalloc heap profiling.
The results are significantly better for IN MEMORY random tests:
random_write_test 1000000000
Elapsed time: 62.39 s
Total inserts: 1000000
Throughput: 16221685.94 bytes/s
Throughput: 16029.33 inserts/s
random_read_test 1000000000
Elapsed time: 197.01 s
Total scanned: 1000000
Throughput: 5136732.38 bytes/s
Throughput: 5075.82 scanned cells/s
So, in memory random read test is only ~2x slower than the number
reported in BigTable paper (although I guess their machine was
somewhat slower 2 years ago).
Without in memory setting, random read test is also ~2x slower:
random_write_test 1000000000
Elapsed time: 65.15 s
Total inserts: 1000000
Throughput: 15533951.97 bytes/s
Throughput: 15349.75 inserts/s
random_read_test 1000000000
Elapsed time: 1256.39 s
Total scanned: 1000000
Throughput: 805479.86 bytes/s
Throughput: 795.93 scanned cells/s
Alex
On Oct 20, 6:59 pm, "Joshua Taylor" <[EMAIL PROTECTED]> wrote:
> Alex, just making sure... you're running the optimized build, right? The
> debug build (which I believe is the default setup) is way slower than the
> optimized build.
>
> Josh
>
> On Mon, Oct 20, 2008 at 6:48 PM, Alex <[EMAIL PROTECTED]> wrote:
>
> > Luke,
>
> > I tried to set IN MEMORY access group option for RandomTest table.
>
> > The result for random read test improved by ~5x:
>
> > random_read_test 1000000000
>
> > 0% 10 20 30 40 50 60 70 80 90 100%
> > |----|----|----|----|----|----|----|----|----|----|
> > ***************************************************
> > Elapsed time: 1971.06 s
> > Total scanned: 1000000
> > Throughput: 513430.49 bytes/s
> > Throughput: 507.34 scanned cells/s
>
> > However, it is still ~2x worse than the number from BigTable paper for
> > non-mem tables and ~20x worse than mem-table.
>
> > Thanks,
> > Alex
>
> > On Oct 19, 2:18 pm, Luke <[EMAIL PROTECTED]> wrote:
> > > The random_read_test used to score 4k qps for comparable benchmark (vs
> > > 1.2k qps in the bigtable paper, note the 10k qps number is for
> > > memtable, which is very different from regular table. In hypertable
> > > you can use the IN MEMORY access group option to get memtable) The
> > > regular table scanner needs to merge scan cell cache, cell stores, so
> > > it's much more expensive than memtable scanner which just scan the
> > > cellcache, regardless the size of the table.
>
> > > Doug pushed out .11, which contains major changes to the way cellcache
> > > and compaction works before he went on a vacation. There might be a
> > > performance regression in recent releases. Thanks for the note, we'll
> > > look into it.
>
> > > __Luke
>
> > > On Oct 16, 9:59 pm, Alex <[EMAIL PROTECTED]> wrote:
>
> > > > Hi All,
>
> > > > Could somebody explain/describe CellCache allocation/eviction policy?
>
> > > > After running random read/write tests, I came to the conclusion that
> > > > CellCache operation is very different from what is described in Google
> > > > BigTable paper, i.e. CellCache works as a write buffer rather than a
> > > > cache. CellCache seems to help a lot for optimizing writes but it
> > > > doesn't help reads.
>
> > > > Here are the results:
>
> > > > random_write_test 100000000
>
> > > > Elapsed time: 8.16 s
> > > > Total inserts: 100000
> > > > Throughput: 12403559.87 bytes/s
> > > > Throughput: 12256.48 inserts/s
>
> > > > random_read_test 100000000
>
> > > > Elapsed time: 1038.47 s
> > > > Total scanned: 100000
> > > > Throughput: 97451.43 bytes/s
> > > > Throughput: 96.30 scanned cells/s
>
> > > > Random read speed is ~100x slower than the result in Google BigTable
> > > > for random read test which fits in the memory. In this case the data
> > > > set size should be ~100MB and should comfortably fit in the DRAM
> > > > (8GB).
>
> > > > Also, tcmalloc heap profiling shows that the usage memory actually
> > > > decreases to ~50MB during random read test while it is >700MB during
> > > > random write test (although top instead shows increase).
>
> > > > I apologize if I am missing something very basic, I have very little
> > > > experience in this area.
>
> > > > Thanks,
> > > > Alex
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