pkg/chunkenc: change default LZ4 buffer size to 64k. #1421
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Added more LZ4 buffer size options for testing. Signed-off-by: Peter Štibraný <peter.stibrany@grafana.com>
Such readers must have allocated twice as many bytes as the block size, and we don't want to pool them and keep that memory allocated. This can happen when reading chunks that were compressed with high buffer size. Signed-off-by: Peter Štibraný <peter.stibrany@grafana.com>
Signed-off-by: Peter Štibraný <peter.stibrany@grafana.com>
Signed-off-by: Peter Štibraný <peter.stibrany@grafana.com>
Signed-off-by: Peter Štibraný <peter.stibrany@grafana.com>
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Also added more LZ4 buffer size options for testing.
What this PR does / why we need it:
LZ4 uses 4M buffer size by default when compressing data. It actually uses twice as much memory for decompression. Even though we pool lz4 readers, it can be a lot of allocated and pooled memory, if there are many concurrent decompressions.
In addition to that, we avoid pooling readers that were used to read chunks compressed with higher block sizes. Reason is that such readers must have used twice as much memory, and we don't want to keep these big-allocations in the pool.
Using smaller buffer doesn't affect (de-)compression time, although it may slightly affect ratio.
Time:
Memory:
Special notes for your reviewer:
"lz4" now defaults to LZ4_64k. Other lz4 buffer sizes are not available for user, but used for testing only.
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