LSM Benchmarks
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This page contains the results of a benchmark test run on the LSM library in several different configurations.

The test uses a single client database connection. It begins with an empty database. The test runs for 200 iterations. Each iteration, the client:

The time taken to insert or retrieve each batch of 50,000 keys is recorded, and transformed to an operations-per-second rate (e.g. if it takes 0.5 seconds to insert 50,000 keys, this is reported as 100,000 operations-per-second). These values are the values reported below. The final database size is roughly 1.2GB.

All tested configurations set the LSM_CONFIG_SAFETY parameter to "normal" and the LSM_CONFIG_MULTIPLE_PROCESSES parameter to zero (single process mode).

Tests were run on a 3.3GHz dual-core PC with 4GB of RAM. The file-system is ext4 on a 7200rpm HDD.

Small Write Buffers Test

The following plot shows the performance of LSM in its default, single-threaded configuration against a multi-threaded deployment.

In the single-threaded mode the in-memory tree is allowed to use up to 1MB of memory before it is flushed to disk, and the database is checkpointed after each 2MB of data is written into the database file.

The multi-threaded configuration launches two background threads as well as the main client thread used to run the test case. One background thread is dedicated to calling lsm_work() (writing data into the database file) and the other to calling lsm_checkpoint() (writing to the database header and syncing the database file). The in-memory tree is declared eligible to be flushed to disk when it uses 1MB of memory. If it grows to 1.5MB, then the client thread is blocked from continuing until the background thread has flushed it to disk. After 2MB of data has been written into the database file it is eligible for checkpointing. Once the database file contains 3MB of uncheckpointed data, the worker thread is prevented from writing any further data to the file until a checkpoint has been completed.

More detail regarding lsm_work() and lsm_checkpoint() is available here.

Large Write Buffers Test

This test is similar to the one above, except with larger write buffers. Specifically, in the single-threaded mode:

And in multi-threaded mode:

Large Write Buffers Test With Pauses

This test is the same as the previous test, except that each iteration the client thread pauses (sleeps) for 2.5 seconds after performing the database inserts and queries.