coreutils/src/yes.c, branch v8.26Mirror of https://https.git.savannah.gnu.org/git/coreutils.git/
https://git.shady.money/coreutils/atom?h=v8.262016-06-24T23:02:08Zmaint: simplify partial writes etc. in 'yes'2016-06-24T23:02:08ZPaul Eggerteggert@cs.ucla.edu2016-06-24T22:58:44Zurn:sha1:4cdb1703aff044de44d27e0558714542197f6dad
* src/yes.c: Include full-write.h.
(main): Use full_write, not write, to simplify handling of partial
writes. Don't bother using stdio to output data; just use
full_write with a buffer as large as needed. Reuse operand
strings if possible, and if the buffer would otherwise be large.
yes: handle short writes2016-06-24T00:13:33ZPádraig BradyP@draigBrady.com2016-06-23T13:15:59Zurn:sha1:5845664c8c61faf004eb3ef9979e770f794108c1
* src/yes.c (main): Loop over the write buffer to
handle the case where write may write less than requested.
* NEWS: Mention the bug fix.
Reported by Paul Eggert.
yes: fix copy and paste issue with previous commit2016-06-24T00:09:28ZPádraig BradyP@draigBrady.com2016-06-24T00:09:28Zurn:sha1:ba5767c2b869dcbbae91f1d42b488dca31652a0a
* src/yes.c (main): Output 'y' not '-'.
* tests/misc/yes.sh: Add a test for default output.
maint: work even if argc == INT_MAX2016-06-23T18:18:03ZPaul Eggerteggert@cs.ucla.edu2016-06-23T18:16:45Zurn:sha1:818b2f48974298065a43a8a2d5355e4aaa65c09d
GCC 7 warned about undefined behavior in this unlikely case.
Problem reported by Jim Meyering in: http://bugs.gnu.org/23825
* src/md5sum.c (main):
* src/paste.c (main):
* src/yes.c (main):
Avoid undefined behavior when argc == INT_MAX.
yes: avoid redundant diagnostics on write error2016-04-21T20:34:00ZPádraig BradyP@draigBrady.com2016-04-04T12:17:34Zurn:sha1:0f5d784bc6c8f63be70cffeaaa88aaca740c3bf6
* src/yes.c (main): For large inputs only write a single
diagnostic for write errors.
* tests/misc/yes.sh: Test when /dev/full is available.
maint: update all copyright year number ranges2016-01-01T14:10:41ZPádraig BradyP@draigBrady.com2016-01-01T14:10:41Zurn:sha1:b16e999f553b682e74e0a56750f649da05130c4f
Run "make update-copyright" and then...
* gnulib: Update to latest with copyright year adjusted.
* tests/init.sh: Sync with gnulib to pick up copyright year.
* bootstrap: Likewise.
* tests/sample-test: Adjust to use the single most recent year.
maint: avoid a new -Werror=return-type warning in yes.c2015-04-28T22:07:13ZPádraig BradyP@draigBrady.com2015-04-28T22:07:13Zurn:sha1:bdf6837655730c09a42cfd0a23c984e1410370f5
* src/yes.c (main): Simplify the logic so that the
compiler can see this function always returns a value.
This was seen with GCC 5.0 in SINGLE_BINARY mode.
yes: improve efficiency when all args aren't buffered2015-03-10T12:30:33ZGiuseppe Scrivanogscrivano@gnu.org2015-03-10T12:25:48Zurn:sha1:e2e11119e0ac653bd0bdab91c189b7803f8df1f0
* src/yes.c (main): Even when the internal buffer isn't large enough,
output what we've buffered already, and interate over the rest.
This improves the performance in the edge case where there are
many small arguments that overflow the buffer.
* tests/misc/yes.sh: Add a test case for the many small arguments case.
yes: output data more efficiently2015-03-10T00:12:30ZPádraig BradyP@draigBrady.com2015-03-09T19:27:32Zurn:sha1:35217221c211f3116f374f305654462195aa634a
yes(1) may be used to generate repeating patterns of text
for test inputs etc., so adjust to be more efficient.
Profiling the case where yes(1) is outputting small items
through stdio (which was the default case), shows the overhead
of continuously processing small items in main() and in stdio:
$ yes >/dev/null & perf top -p $!
31.02% yes [.] main
27.36% libc-2.20.so [.] _IO_file_xsputn@@GLIBC_2.2.5
14.51% libc-2.20.so [.] fputs_unlocked
13.50% libc-2.20.so [.] strlen
10.66% libc-2.20.so [.] __GI___mempcpy
1.98% yes [.] fputs_unlocked@plta
Sending more data per stdio call improves the situation,
but still, there is significant stdio overhead due to memory copies,
and the repeated string length checking:
$ yes "`echo {1..1000}`" >/dev/null & perf top -p $!
42.26% libc-2.20.so [.] __GI___mempcpy
17.38% libc-2.20.so [.] strlen
5.21% [kernel] [k] __srcu_read_lock
4.58% [kernel] [k] __srcu_read_unlock
4.27% libc-2.20.so [.] _IO_file_xsputn@@GLIBC_2.2.5
2.50% libc-2.20.so [.] __GI___libc_write
2.45% [kernel] [k] system_call
2.40% [kernel] [k] system_call_after_swapgs
2.27% [kernel] [k] vfs_write
2.09% libc-2.20.so [.] _IO_do_write@@GLIBC_2.2.5
2.01% [kernel] [k] fsnotify
1.95% libc-2.20.so [.] _IO_file_write@@GLIBC_2.2.5
1.44% yes [.] main
We can avoid all stdio overhead by building up the buffer
_once_ and outputting that, and the profile below shows
the bottleneck moved to the kernel:
$ src/yes >/dev/null & perf top -p $!
15.42% [kernel] [k] __srcu_read_lock
12.98% [kernel] [k] __srcu_read_unlock
9.41% libc-2.20.so [.] __GI___libc_write
9.11% [kernel] [k] vfs_write
8.35% [kernel] [k] fsnotify
8.02% [kernel] [k] system_call
5.84% [kernel] [k] system_call_after_swapgs
4.54% [kernel] [k] __fget_light
3.98% [kernel] [k] sys_write
3.65% [kernel] [k] selinux_file_permission
3.44% [kernel] [k] rw_verify_area
2.94% [kernel] [k] __fsnotify_parent
2.76% [kernel] [k] security_file_permission
2.39% yes [.] main
2.17% [kernel] [k] __fdget_pos
2.13% [kernel] [k] sysret_check
0.81% [kernel] [k] write_null
0.36% yes [.] write@plt
Note this change also ensures that yes(1) will only write
complete lines for lines shorter than BUFSIZ.
* src/yes.c (main): Build up a BUFSIZ buffer of lines,
and output that, rather than having stdio process each item.
* tests/misc/yes.sh: Add a new test for various buffer sizes.
* tests/local.mk: Reference the new test.
Fixes http://bugs.gnu.org/20029
maint: update all copyright year number ranges2015-01-01T04:52:17ZPádraig BradyP@draigBrady.com2015-01-01T04:49:02Zurn:sha1:e0afeb0099c899c2caa7453072e2d223d8f0ceb9
Run "make update-copyright" and then...
* tests/sample-test: Adjust to use the single most recent year.
* tests/du/bind-mount-dir-cycle-v2.sh: Fix case in copyright message,
so that year is updated automatically in future.