Hi All, Earlier this week I was examining why operf was not properly mapping samples from anonymous regions to Java methods when the JVM was using the older hugepage page mechanism which has a static pool of pages when the machine sets up. I tracked the problem down to the the PERF_RECORD_MMAP entries being different between regular and hugepages.
A hugepage PERF_RECORD_MMAP entry from "perf report -D" when hugepages were used: 0x125d60 [0x58]: event: 1 . . ... raw event: size 88 bytes . 0000: 01 00 00 00 02 00 58 00 36 29 00 00 37 29 00 00 ......X.6)..7).. . 0010: 00 00 c0 aa aa 2a 00 00 00 00 00 03 00 00 00 00 .....*.......... . 0020: 00 00 00 00 00 00 00 00 2f 61 6e 6f 6e 5f 68 75 ......../anon_hu . 0030: 67 65 70 61 67 65 20 28 64 65 6c 65 74 65 64 29 gepage (deleted) . 0040: 00 00 00 00 00 00 00 00 36 29 00 00 37 29 00 00 ........6)..7).. . 0050: cd 0f 4c 7e a7 b2 00 00 ..L~.... . 196432448196557 0x125d60 [0x58]: PERF_RECORD_MMAP 10550/10551: [0x2aaaaac00000(0x3000000) @ 0]: /anon_hugepage (deleted) Below is a PERF_RECORD_MMAP for normal page sized pages anonymous region: 0xd8 [0x50]: event: 1 . . ... raw event: size 80 bytes . 0000: 01 00 00 00 01 00 50 00 ff ff ff ff 00 00 00 00 ......P......... ...skipping... . 0020: 00 00 00 a9 f9 7f 00 00 2f 2f 61 6e 6f 6e 00 00 ........//anon.. . 0030: 3f 2a 00 00 40 2a 00 00 68 f9 4a f5 20 b3 00 00 ?*..@*..h.J. ... . 196954135656808 0x1873c8 [0x40]: PERF_RECORD_MMAP 10815/10816: [0x7ff9a9000000(0x270000) @ 0x7ff9a9000000]: //anon Why the distinction between the two memory mappings in this manner? Why not just generate same output for the hugepage PERF_RECORD_MMAP? Also why does it include the " (deleted)" suffix for the hugepage entry? I don't think that the mapping had been removed when that entry was generated? -Will -- To unsubscribe from this list: send the line "unsubscribe linux-perf-users" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
