On 05/09/17 01:36, Kamil Dudka wrote: > On Thursday, December 10, 2015 2:26:38 AM CEST Pádraig Brady wrote: >> On 09/12/15 10:35, Pádraig Brady wrote: >>> On 09/12/15 06:34, Kamil Dudka wrote: >>>> The flag is needed to implement the -noleaf option of find. >>>> * lib/fts.c (link_count_optimize_ok): Implement the FTS_NOLEAF flag. >>>> * lib/fts_.h (FTS_NOLEAF): New macro, shifted conflicting constants. >>> >>> Is this exposed to fix issues with certain file systems, >>> or just in case there may be issues, or support easily >>> testing find without the leaf optimization? >>> >>> I see Jim said the current FTS implementation >>> would make -noleaf a no-op there: >>> https://lists.gnu.org/archive/html/bug-gnulib/2008-12/msg00280.html >>> >>> cheers, >>> Pádraig. >>> >>> p.s. I see that find does a stat per file on XFS, >>> while d_type can be used to distinguish dirs there. >>> On XFS DT_DIR is set for dirs and DT_UNKNOWN otherwise. >>> I wonder is there some optimization we could do for that case. >> >> I did a quick check on XFS which suggests the leaf optimization >> based on st_nlink is valid: >> test $(($(find . -maxdepth 1 -type d | wc -l) + 1)) = $(stat -c %h .) && >> echo leaf_ok >> >> Applying this diff: >> @@ -717,6 +718,7 @@ leaf_optimization_applies (int dir_fd) >> { >> /* List here the file system types that lack usable dirent.d_type >> info, yet for which the optimization does apply. */ >> + case S_MAGIC_XFS: >> case S_MAGIC_REISERFS: >> return true; >> >> Gives this significant speedup: >> $ time find/find-before /usr/share >/dev/null >> real 0m0.410s >> user 0m0.145s >> sys 0m0.266s >> >> $ time find/find-after /usr/share >/dev/null >> real 0m0.278s >> user 0m0.147s >> sys 0m0.131s > > Pádraig, do you remember which kernel you tested it with? > > I am currently not able to get any speedup on XFS with Fedora/el7 kernels...
Eek that's getting towards 2 years ago :) I _vaguely_ remember creating a loopback XFS for testing on Fedora. Me goes spelunking on an old laptop... Ah found a perf.data indicating 4.2.5-300.fc23.x86_64 (glibc-2.22) I don't have the code changes though I vaguely remember having to tweak things so that the gnulib FTS was used. cheers, Pádraig
