rocksdb/utilities/write_batch_with_index
mrambacher 3dff28cf9b Use SystemClock* instead of std::shared_ptr<SystemClock> in lower level routines (#8033)
Summary:
For performance purposes, the lower level routines were changed to use a SystemClock* instead of a std::shared_ptr<SystemClock>.  The shared ptr has some performance degradation on certain hardware classes.

For most of the system, there is no risk of the pointer being deleted/invalid because the shared_ptr will be stored elsewhere.  For example, the ImmutableDBOptions stores the Env which has a std::shared_ptr<SystemClock> in it.  The SystemClock* within the ImmutableDBOptions is essentially a "short cut" to gain access to this constant resource.

There were a few classes (PeriodicWorkScheduler?) where the "short cut" property did not hold.  In those cases, the shared pointer was preserved.

Using db_bench readrandom perf_level=3 on my EC2 box, this change performed as well or better than 6.17:

6.17: readrandom   :      28.046 micros/op 854902 ops/sec;   61.3 MB/s (355999 of 355999 found)
6.18: readrandom   :      32.615 micros/op 735306 ops/sec;   52.7 MB/s (290999 of 290999 found)
PR: readrandom   :      27.500 micros/op 871909 ops/sec;   62.5 MB/s (367999 of 367999 found)

(Note that the times for 6.18 are prior to revert of the SystemClock).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8033

Reviewed By: pdillinger

Differential Revision: D27014563

Pulled By: mrambacher

fbshipit-source-id: ad0459eba03182e454391b5926bf5cdd45657b67
2021-03-15 04:34:11 -07:00
..
write_batch_with_index_internal.cc Use SystemClock* instead of std::shared_ptr<SystemClock> in lower level routines (#8033) 2021-03-15 04:34:11 -07:00
write_batch_with_index_internal.h Eliminate the creation of ImmutableDBOptions in WBWI::GetFromBatch (#6851) 2021-01-04 09:05:46 -08:00
write_batch_with_index_test.cc Add further tests to ASSERT_STATUS_CHECKED (1) (#7679) 2020-12-08 15:55:04 -08:00
write_batch_with_index.cc Eliminate the creation of ImmutableDBOptions in WBWI::GetFromBatch (#6851) 2021-01-04 09:05:46 -08:00