2016-06-13 13:12 GMT+08:00 Sergey Senozhatsky <sergey.senozhatsky.work@xxxxxxxxx>: > Hello, > > On (06/13/16 13:42), Minchan Kim wrote: > [..] >> > compacted(total 0) */ >> > 2) # 1351.241 us | } >> > ------ >> > => 1351.241 us used >> > >> > And it seems the overhead of function_graph is bigger than trace event. >> > >> > bash-3682 [002] .... 1439.180646: zsmalloc_compact_start: pool zram0 >> > bash-3682 [002] .... 1439.180659: zsmalloc_compact_end: pool zram0: >> > 0 pages compacted(total 0) >> > => 13 us > 1351.241 us >> >> You could use set_ftrace_filter to cut out. >> >> To introduce new event trace to get a elasped time, it's pointless, >> I think. >> >> It should have more like pool name you mentioned. >> Like saying other thread, It would be better to show >> [pool name, compact size_class, >> the number of object moved, the number of freed page], IMO. > > just my 5 cents: > > some parts (of the info above) are already available: zram<ID> maps to > pool<ID> name, which maps to a sysfs file name, that can contain the rest. > I'm just trying to understand what kind of optimizations we are talking > about here and how would timings help... compaction can spin on class > lock, for example, if the device in question is busy, etc. etc. on the > other hand we have a per-class info in zsmalloc pool stats output, so > why not extend it instead of introducing a new debugging interface? I've considered adding new interface in /sys/../zsmalloc/ or uasing trace_mm_shrink_slab_[start/end] to get such information. But none of them can cover all the cases: 1) distinguish which zs pool is compacted. 2) freed pages of zs_compact(), total freed pages of zs_compact() 3) realtime log printed Actually, the trace event added in zs_compact not only just for debugging/optimization inside zsmalloc, but also for system level. We can do some analysis by combining data from zs_compac(), system information(like free mem, swap info, LMK, etc) Thanks. > > -ss -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>