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perf: add command for measuring revlog chunk operations...
perf: add command for measuring revlog chunk operations Upcoming commits will teach revlogs to leverage the new compression engine API so that new compression formats can more easily be leveraged in revlogs. We want to be sure this refactoring doesn't regress performance. So this commit introduces "perfrevchunks" to explicitly test performance of reading, decompressing, and recompressing revlog chunks. Here is output when run on the mozilla-unified repo: $ hg perfrevlogchunks -c ! read ! wall 0.346603 comb 0.350000 user 0.340000 sys 0.010000 (best of 28) ! read w/ reused fd ! wall 0.337707 comb 0.340000 user 0.320000 sys 0.020000 (best of 30) ! read batch ! wall 0.013206 comb 0.020000 user 0.000000 sys 0.020000 (best of 221) ! read batch w/ reused fd ! wall 0.013259 comb 0.030000 user 0.010000 sys 0.020000 (best of 222) ! chunk ! wall 1.909939 comb 1.910000 user 1.900000 sys 0.010000 (best of 6) ! chunk batch ! wall 1.750677 comb 1.760000 user 1.740000 sys 0.020000 (best of 6) ! compress ! wall 5.668004 comb 5.670000 user 5.670000 sys 0.000000 (best of 3) $ hg perfrevlogchunks -m ! read ! wall 0.365834 comb 0.370000 user 0.350000 sys 0.020000 (best of 26) ! read w/ reused fd ! wall 0.350160 comb 0.350000 user 0.320000 sys 0.030000 (best of 28) ! read batch ! wall 0.024777 comb 0.020000 user 0.000000 sys 0.020000 (best of 119) ! read batch w/ reused fd ! wall 0.024895 comb 0.030000 user 0.000000 sys 0.030000 (best of 118) ! chunk ! wall 2.514061 comb 2.520000 user 2.480000 sys 0.040000 (best of 4) ! chunk batch ! wall 2.380788 comb 2.380000 user 2.360000 sys 0.020000 (best of 5) ! compress ! wall 9.815297 comb 9.820000 user 9.820000 sys 0.000000 (best of 3) We already see some interesting data, such as how much slower non-batched chunk reading is and that zlib compression appears to be >2x slower than decompression. I didn't have the data when I wrote this commit message, but I ran this on Mozilla's NFS-based Mercurial server and the time for reading with a reused file descriptor was faster. So I think it is worth testing both with and without file descriptor reuse so we can make informed decisions about recycling file descriptors.

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r29255:b0b85d86 stable
r30451:94ca0e13 default
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test-cache-abuse.t
100 lines | 2.4 KiB | text/troff | Tads3Lexer
Enable obsolete markers
$ cat >> $HGRCPATH << EOF
> [experimental]
> evolution=createmarkers
> [phases]
> publish=False
> EOF
Build a repo with some cacheable bits:
$ hg init a
$ cd a
$ echo a > a
$ hg ci -qAm0
$ hg tag t1
$ hg book -i bk1
$ hg branch -q b2
$ hg ci -Am1
$ hg tag t2
$ echo dumb > dumb
$ hg ci -qAmdumb
$ hg debugobsolete b1174d11b69e63cb0c5726621a43c859f0858d7f
$ hg phase -pr t1
$ hg phase -fsr t2
Make a helper function to check cache damage invariants:
- command output shouldn't change
- cache should be present after first use
- corruption/repair should be silent (no exceptions or warnings)
- cache should survive deletion, overwrite, and append
- unreadable / unwriteable caches should be ignored
- cache should be rebuilt after corruption
$ damage() {
> CMD=$1
> CACHE=.hg/cache/$2
> CLEAN=$3
> hg $CMD > before
> test -f $CACHE || echo "not present"
> echo bad > $CACHE
> test -z "$CLEAN" || $CLEAN
> hg $CMD > after
> diff -u before after || echo "*** overwrite corruption"
> echo corruption >> $CACHE
> test -z "$CLEAN" || $CLEAN
> hg $CMD > after
> diff -u before after || echo "*** append corruption"
> rm $CACHE
> mkdir $CACHE
> test -z "$CLEAN" || $CLEAN
> hg $CMD > after
> diff -u before after || echo "*** read-only corruption"
> test -d $CACHE || echo "*** directory clobbered"
> rmdir $CACHE
> test -z "$CLEAN" || $CLEAN
> hg $CMD > after
> diff -u before after || echo "*** missing corruption"
> test -f $CACHE || echo "not rebuilt"
> }
Beat up tags caches:
$ damage "tags --hidden" tags2
$ damage tags tags2-visible
$ damage "tag -f t3" hgtagsfnodes1
Beat up hidden cache:
$ damage log hidden
Beat up branch caches:
$ damage branches branch2-base "rm .hg/cache/branch2-[vs]*"
$ damage branches branch2-served "rm .hg/cache/branch2-[bv]*"
$ damage branches branch2-visible
$ damage "log -r branch(.)" rbc-names-v1
$ damage "log -r branch(default)" rbc-names-v1
$ damage "log -r branch(b2)" rbc-revs-v1
We currently can't detect an rbc cache with unknown names:
$ damage "log -qr branch(b2)" rbc-names-v1
--- before * (glob)
+++ after * (glob)
@@ -1,8 +?,0 @@ (glob)
-2:5fb7d38b9dc4
-3:60b597ffdafa
-4:b1174d11b69e
-5:6354685872c0
-6:5ebc725f1bef
-7:7b76eec2f273
-8:ef3428d9d644
-9:ba7a936bc03c
*** append corruption