Mercurial > hg-stable
view tests/test-debugbuilddag.t @ 26379:39d643252b9f
revlog: use existing file handle when reading during _addrevision
_addrevision() may need to read from revlogs as part of computing
deltas. Previously, we would flush existing file handles and open
a new, short-lived file handle to perform the reading.
If we have an existing file handle, it seems logical to reuse it
for reading instead of opening a new file handle. This patch
makes that the new behavior.
After this patch, revlog files are only reopened when adding
revisions if the revlog is switched from inline to non-inline.
On Linux when unbundling a bundle of the mozilla-central repo, this
patch has the following impact on system call counts:
Call Before After Delta
write 827,639 673,390 -154,249
open 700,103 684,089 -16,014
read 74,489 74,489 0
fstat 493,924 461,896 -32,028
close 249,131 233,117 -16,014
stat 242,001 242,001 0
lstat 18,676 18,676 0
lseek 20,268 20,268 0
ioctl 14,652 13,173 -1,479
TOTAL 3,180,758 2,930,679 -250,079
It's worth noting that many of the open() calls fail due to missing
files. That's why there are many more open() calls than close().
Despite the significant system call reduction, this change does not
seem to have a significant performance impact on Linux.
On Windows 10 (not a VM, on a SSD), this patch appears to reduce
unbundle time for mozilla-central from ~960s to ~920s. This isn't
as significant as I was hoping. But a decrease it is nonetheless.
Still, Windows unbundle performance is still >2x slower than Linux.
Despite the lack of significant gains, fewer system calls is fewer
system calls. If nothing else, this will narrow the focus of potential
areas to optimize in the future.
| author | Gregory Szorc <gregory.szorc@gmail.com> |
|---|---|
| date | Sun, 27 Sep 2015 16:08:18 -0700 |
| parents | 95f490136e75 |
| children | 8d6109b49b31 |
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plain $ hg init $ hg debugbuilddag '+2:f +3:p2 @temp <f+4 @default /p2 +2' \ > --config extensions.progress= --config progress.assume-tty=1 \ > --config progress.delay=0 --config progress.refresh=0 \ > --config progress.format=topic,bar,number \ > --config progress.width=60 \r (no-eol) (esc) building [ ] 0/12\r (no-eol) (esc) building [ ] 0/12\r (no-eol) (esc) building [==> ] 1/12\r (no-eol) (esc) building [==> ] 1/12\r (no-eol) (esc) building [======> ] 2/12\r (no-eol) (esc) building [=========> ] 3/12\r (no-eol) (esc) building [=============> ] 4/12\r (no-eol) (esc) building [=============> ] 4/12\r (no-eol) (esc) building [=============> ] 4/12\r (no-eol) (esc) building [================> ] 5/12\r (no-eol) (esc) building [====================> ] 6/12\r (no-eol) (esc) building [=======================> ] 7/12\r (no-eol) (esc) building [===========================> ] 8/12\r (no-eol) (esc) building [===========================> ] 8/12\r (no-eol) (esc) building [==============================> ] 9/12\r (no-eol) (esc) building [==================================> ] 10/12\r (no-eol) (esc) building [=====================================> ] 11/12\r (no-eol) (esc) \r (no-eol) (esc) tags $ cat .hg/localtags 66f7d451a68b85ed82ff5fcc254daf50c74144bd f bebd167eb94d257ace0e814aeb98e6972ed2970d p2 dag $ hg debugdag -t -b +2:f +3:p2 @temp*f+3 @default*/p2+2:tip tip $ hg id 000000000000 glog $ hg log -G --template '{rev}: {desc} [{branches}] @ {date}\n' o 11: r11 [] @ 11.00 | o 10: r10 [] @ 10.00 | o 9: r9 [] @ 9.00 |\ | o 8: r8 [temp] @ 8.00 | | | o 7: r7 [temp] @ 7.00 | | | o 6: r6 [temp] @ 6.00 | | | o 5: r5 [temp] @ 5.00 | | o | 4: r4 [] @ 4.00 | | o | 3: r3 [] @ 3.00 | | o | 2: r2 [] @ 2.00 |/ o 1: r1 [] @ 1.00 | o 0: r0 [] @ 0.00 overwritten files, starting on a non-default branch $ rm -r .hg $ hg init $ hg debugbuilddag '@start.@default.:f +3:p2 @temp <f+4 @default /p2 +2' -q -o tags $ cat .hg/localtags f778700ebd50fcf282b23a4446bd155da6453eb6 f bbccf169769006e2490efd2a02f11c3d38d462bd p2 dag $ hg debugdag -t -b @start+1 @default+1:f +3:p2 @temp*f+3 @default*/p2+2:tip tip $ hg id 000000000000 glog $ hg log -G --template '{rev}: {desc} [{branches}] @ {date}\n' o 11: r11 [] @ 11.00 | o 10: r10 [] @ 10.00 | o 9: r9 [] @ 9.00 |\ | o 8: r8 [temp] @ 8.00 | | | o 7: r7 [temp] @ 7.00 | | | o 6: r6 [temp] @ 6.00 | | | o 5: r5 [temp] @ 5.00 | | o | 4: r4 [] @ 4.00 | | o | 3: r3 [] @ 3.00 | | o | 2: r2 [] @ 2.00 |/ o 1: r1 [] @ 1.00 | o 0: r0 [start] @ 0.00 glog of $ hg log -G --template '{rev}: {desc} [{branches}]\n' of o 11: r11 [] | o 10: r10 [] | o 9: r9 [] |\ | o 8: r8 [temp] | | | o 7: r7 [temp] | | | o 6: r6 [temp] | | | o 5: r5 [temp] | | o | 4: r4 [] | | o | 3: r3 [] | | o | 2: r2 [] |/ o 1: r1 [] | o 0: r0 [start] tags $ hg tags -v tip 11:9ffe238a67a2 p2 4:bbccf1697690 local f 1:f778700ebd50 local cat of $ hg cat of --rev tip r11 new and mergeable files $ rm -r .hg $ hg init $ hg debugbuilddag '+2:f +3:p2 @temp <f+4 @default /p2 +2' -q -mn dag $ hg debugdag -t -b +2:f +3:p2 @temp*f+3 @default*/p2+2:tip tip $ hg id 000000000000 glog $ hg log -G --template '{rev}: {desc} [{branches}] @ {date}\n' o 11: r11 [] @ 11.00 | o 10: r10 [] @ 10.00 | o 9: r9 [] @ 9.00 |\ | o 8: r8 [temp] @ 8.00 | | | o 7: r7 [temp] @ 7.00 | | | o 6: r6 [temp] @ 6.00 | | | o 5: r5 [temp] @ 5.00 | | o | 4: r4 [] @ 4.00 | | o | 3: r3 [] @ 3.00 | | o | 2: r2 [] @ 2.00 |/ o 1: r1 [] @ 1.00 | o 0: r0 [] @ 0.00 glog mf $ hg log -G --template '{rev}: {desc} [{branches}]\n' mf o 11: r11 [] | o 10: r10 [] | o 9: r9 [] |\ | o 8: r8 [temp] | | | o 7: r7 [temp] | | | o 6: r6 [temp] | | | o 5: r5 [temp] | | o | 4: r4 [] | | o | 3: r3 [] | | o | 2: r2 [] |/ o 1: r1 [] | o 0: r0 [] man r4 $ hg manifest -r4 mf nf0 nf1 nf2 nf3 nf4 cat r4 mf $ hg cat -r4 mf 0 r0 1 2 r1 3 4 r2 5 6 r3 7 8 r4 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 man r8 $ hg manifest -r8 mf nf0 nf1 nf5 nf6 nf7 nf8 cat r8 mf $ hg cat -r8 mf 0 r0 1 2 r1 3 4 5 6 7 8 9 10 r5 11 12 r6 13 14 r7 15 16 r8 17 18 19 20 21 22 23 man $ hg manifest --rev tip mf nf0 nf1 nf10 nf11 nf2 nf3 nf4 nf5 nf6 nf7 nf8 nf9 cat mf $ hg cat mf --rev tip 0 r0 1 2 r1 3 4 r2 5 6 r3 7 8 r4 9 10 r5 11 12 r6 13 14 r7 15 16 r8 17 18 r9 19 20 r10 21 22 r11 23