Improve statistics

Summary:
This adds more statistics to be reported by GetProperty("leveldb.stats").
The new stats include time spent waiting on stalls in MakeRoomForWrite.
This also includes the total amplification rate where that is:
    (#bytes of sequential IO during compaction) / (#bytes from Put)
This also includes a lot more data for the per-level compaction report.
* Rn(MB) - MB read from level N during compaction between levels N and N+1
* Rnp1(MB) - MB read from level N+1 during compaction between levels N and N+1
* Wnew(MB) - new data written to the level during compaction
* Amplify - ( Write(MB) + Rnp1(MB) ) / Rn(MB)
* Rn - files read from level N during compaction between levels N and N+1
* Rnp1 - files read from level N+1 during compaction between levels N and N+1
* Wnp1 - files written to level N+1 during compaction between levels N and N+1
* NewW - new files written to level N+1 during compaction
* Count - number of compactions done for this level

This is the new output from DB::GetProperty("leveldb.stats"). The old output stopped at Write(MB)

                               Compactions
Level  Files Size(MB) Time(sec) Read(MB) Write(MB)  Rn(MB) Rnp1(MB) Wnew(MB) Amplify Read(MB/s) Write(MB/s)   Rn Rnp1 Wnp1 NewW Count
-------------------------------------------------------------------------------------------------------------------------------------
  0        3        6        33        0       576       0        0      576    -1.0       0.0         1.3     0    0    0    0   290
  1      127      242       351     5316      5314     570     4747      567    17.0      12.1        12.1   287 2399 2685  286    32
  2      161      328        54      822       824     326      496      328     4.0       1.9         1.9   160  251  411  160   161
Amplification: 22.3 rate, 0.56 GB in, 12.55 GB out
Uptime(secs): 439.8
Stalls(secs): 206.938 level0_slowdown, 0.000 level0_numfiles, 24.129 memtable_compaction

Task ID: #

Blame Rev:

Test Plan:
run db_bench

Revert Plan:

Database Impact:

Memcache Impact:

Other Notes:

EImportant:

- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -
(cherry picked from commit ecdeead38f86cc02e754d0032600742c4f02fec8)

Reviewers: dhruba

Differential Revision: https://reviews.facebook.net/D6153
This commit is contained in:
Mark Callaghan
2012-10-23 10:34:09 -07:00
parent 51d2adfbeb
commit e7206f43ee
3 changed files with 154 additions and 32 deletions

View File

@@ -213,21 +213,57 @@ class DBImpl : public DB {
// last time when DeleteObsoleteFiles was invoked
uint64_t delete_obsolete_files_last_run_;
// These count the number of microseconds for which MakeRoomForWrite stalls.
uint64_t stall_level0_slowdown_;
uint64_t stall_memtable_compaction_;
uint64_t stall_level0_num_files_;
// Time at which this instance was started.
const uint64_t started_at_;
// Per level compaction stats. stats_[level] stores the stats for
// compactions that produced data for the specified "level".
struct CompactionStats {
int64_t micros;
int64_t bytes_read;
// Bytes read from level N during compaction between levels N and N+1
int64_t bytes_readn;
// Bytes read from level N+1 during compaction between levels N and N+1
int64_t bytes_readnp1;
// Total bytes written during compaction between levels N and N+1
int64_t bytes_written;
CompactionStats() : micros(0), bytes_read(0), bytes_written(0) { }
// Files read from level N during compaction between levels N and N+1
int files_in_leveln;
// Files read from level N+1 during compaction between levels N and N+1
int files_in_levelnp1;
// Files written during compaction between levels N and N+1
int files_out_levelnp1;
// Number of compactions done
int count;
CompactionStats() : micros(0), bytes_readn(0), bytes_readnp1(0),
bytes_written(0), files_in_leveln(0),
files_in_levelnp1(0), files_out_levelnp1(0),
count(0) { }
void Add(const CompactionStats& c) {
this->micros += c.micros;
this->bytes_read += c.bytes_read;
this->bytes_readn += c.bytes_readn;
this->bytes_readnp1 += c.bytes_readnp1;
this->bytes_written += c.bytes_written;
this->files_in_leveln += c.files_in_leveln;
this->files_in_levelnp1 += c.files_in_levelnp1;
this->files_out_levelnp1 += c.files_out_levelnp1;
this->count += 1;
}
};
CompactionStats* stats_;
static const int KEEP_LOG_FILE_NUM = 1000;