On Thu, Feb 23, 2023 at 12:04:45PM +0900, Sergey Senozhatsky wrote: > Hi, > > Existing zsmalloc page fullness grouping leads to suboptimal page > selection for both zs_malloc() and zs_compact(). This patchset > reworks zsmalloc fullness grouping/classification. > > Additinally it also implements new compaction algorithm that is > expected to use CPU-cycles (as it potentially does fewer memcpy-s > in zs_object_copy()). > > TEST > ==== > > It's very challenging to reliably test this series. I ended up > developing my own synthetic test that has 100% reproducibility. > The test generates significan fragmentation (for each size class) > and then performs compaction for each class individually and tracks > the number of memcpy() in zs_object_copy(), so that we can compare > the amount work compaction does on per-class basis. > > Total amount of work (zram mm_stat objs_moved) > ---------------------------------------------- > > Old fullness grouping, old compaction algorithm: > 323977 memcpy() in zs_object_copy(). > > Old fullness grouping, new compaction algorithm: > 262944 memcpy() in zs_object_copy(). > > New fullness grouping, new compaction algorithm: > 213978 memcpy() in zs_object_copy(). > > > Per-class compaction memcpy() comparison (T-test) Just curiosity: What's the T-test? > ------------------------------------------------- > > x Old fullness grouping, old compaction algorithm > + Old fullness grouping, new compaction algorithm > > N Min Max Median Avg Stddev > x 140 349 3513 2461 2314.1214 806.03271 > + 140 289 2778 2006 1878.1714 641.02073 > Difference at 95.0% confidence > -435.95 +/- 170.595 > -18.8387% +/- 7.37193% > (Student's t, pooled s = 728.216) > > > x Old fullness grouping, old compaction algorithm > + New fullness grouping, new compaction algorithm > > N Min Max Median Avg Stddev > x 140 349 3513 2461 2314.1214 806.03271 > + 140 226 2279 1644 1528.4143 524.85268 > Difference at 95.0% confidence > -785.707 +/- 159.331 > -33.9527% +/- 6.88516% > (Student's t, pooled s = 680.132) What's the different with result above? Did you just run two times and shows they are consistent or this is new result based on different testing? Anyway, this is really nice improvement. The comment I had in thread are just minors. Thanks, Sergey!
