@@ -30,6 +30,27 @@ if test $# -gt 0 -o ! -d "$srctree"; then
usage
fi
+try_tag() {
+ tag="$1"
+
+ # Is $tag an annotated tag?
+ [ "$(git cat-file -t "$tag" 2> /dev/null)" = tag ] || return 1
+
+ # Is it an ancestor of HEAD, and if so, how many commits are in $tag..HEAD?
+ # shellcheck disable=SC2046 # word splitting is the point here
+ set -- $(git rev-list --count --left-right "$tag"...HEAD 2> /dev/null)
+
+ # $1 is 0 if and only if $tag is an ancestor of HEAD. Use
+ # string comparison, because $1 is empty if the 'git rev-list'
+ # command somehow failed.
+ [ "$1" = 0 ] || return 1
+
+ # $2 is the number of commits in the range $tag..HEAD, possibly 0.
+ count="$2"
+
+ return 0
+}
+
scm_version()
{
local short=false
@@ -64,30 +85,27 @@ scm_version()
# If a localversion* file exists, and the corresponding
# annotated tag exists and is an ancestor of HEAD, use
# it. This is the case in linux-next.
- tag=${file_localversion#-}
- desc=
- if [ -n "${tag}" ]; then
- desc=$(git describe --match=$tag 2>/dev/null)
- fi
-
+ if [ -n "${file_localversion#-}" ] && try_tag "${file_localversion#-}" ; then
+ :
# Otherwise, if a localversion* file exists, and the tag
# obtained by appending it to the tag derived from
# KERNELVERSION exists and is an ancestor of HEAD, use
# it. This is e.g. the case in linux-rt.
- if [ -z "${desc}" ] && [ -n "${file_localversion}" ]; then
- tag="${version_tag}${file_localversion}"
- desc=$(git describe --match=$tag 2>/dev/null)
- fi
-
+ elif [ -n "${file_localversion}" ] && try_tag "${version_tag}${file_localversion}" ; then
+ :
# Otherwise, default to the annotated tag derived from KERNELVERSION.
- if [ -z "${desc}" ]; then
- tag="${version_tag}"
- desc=$(git describe --match=$tag 2>/dev/null)
+ elif try_tag "${version_tag}" ; then
+ :
+ else
+ count=
fi
- # If we are at the tagged commit, we ignore it because the version is
- # well-defined.
- if [ "${tag}" != "${desc}" ]; then
+ # If we are at the tagged commit, we ignore it because the
+ # version is well-defined. If none of the attempted tags exist
+ # or were usable, $count is empty, so there is no count to
+ # pretty-print, but we can and should still append the -g plus
+ # the abbreviated sha1.
+ if [ "${count}" != 0 ]; then
# If only the short version is requested, don't bother
# running further git commands
@@ -95,14 +113,15 @@ scm_version()
echo "+"
return
fi
+
# If we are past the tagged commit, we pretty print it.
# (like 6.1.0-14595-g292a089d78d3)
- if [ -n "${desc}" ]; then
- echo "${desc}" | awk -F- '{printf("-%05d", $(NF-1))}'
+ if [ -n "${count}" ]; then
+ printf "%s%05d" "-" "${count}"
fi
# Add -g and exactly 12 hex chars.
- printf '%s%s' -g "$(echo $head | cut -c1-12)"
+ printf '%s%.12s' -g "$head"
fi
if ${no_dirty}; then
Contrary to expectations, passing a single candidate tag to "git describe" is slower than not passing any --match options. $ time git describe --debug ... traversed 10619 commits ... v6.12-rc5-63-g0fc810ae3ae1 real 0m0.169s $ time git describe --match=v6.12-rc5 --debug ... traversed 1310024 commits v6.12-rc5-63-g0fc810ae3ae1 real 0m1.281s In fact, the --debug output shows that git traverses all or most of history. For some repositories and/or git versions, those 1.3s are actually 10-15 seconds. This has been acknowledged as a performance bug in git [1], and a fix is on its way [2]. However, no solution is yet in git.git, and even when one lands, it will take quite a while before it finds its way to a release and for $random_kernel_developer to pick that up. So rewrite the logic to use plumbing commands. For each of the candidate values of $tag, we ask: (1) is $tag even an annotated tag? (2) Is it eligible to describe HEAD, i.e. an ancestor of HEAD? (3) If so, how many commits are in $tag..HEAD? I have tested that this produces the same output as the current script for ~700 random commits between v6.9..v6.10. For those 700 commits, and in my git repo, the 'make -s kernelrelease' command is on average ~4 times faster with this patch applied (geometric mean of ratios). For the commit mentioned in Josh's original report [3], the time-consuming part of setlocalversion goes from $ time git describe --match=v6.12-rc5 c1e939a21eb1 v6.12-rc5-44-gc1e939a21eb1 real 0m1.210s to $ time git rev-list --count --left-right v6.12-rc5..c1e939a21eb1 0 44 real 0m0.037s [1] https://lore.kernel.org/git/20241101113910.GA2301440@coredump.intra.peff.net/ [2] https://lore.kernel.org/git/20241106192236.GC880133@coredump.intra.peff.net/ [3] https://lore.kernel.org/lkml/309549cafdcfe50c4fceac3263220cc3d8b109b2.1730337435.git.jpoimboe@kernel.org/ Reported-by: Sean Christopherson <seanjc@google.com> Closes: https://lore.kernel.org/lkml/ZPtlxmdIJXOe0sEy@google.com/ Reported-by: Josh Poimboeuf <jpoimboe@kernel.org> Closes: https://lore.kernel.org/lkml/309549cafdcfe50c4fceac3263220cc3d8b109b2.1730337435.git.jpoimboe@kernel.org/ Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> --- v4: - Switch the logic to make use of the return values from try_tag, instead of asking whether $count has been set. - Update a comment. - Drop T-b tag from Josh as I think this changes the flow sufficiently from the version he tested. I have repeated my tests, with the same functional and performance result as indicated in the commit log. v3: https://lore.kernel.org/lkml/20241118110154.3711777-1-linux@rasmusvillemoes.dk/ scripts/setlocalversion | 59 +++++++++++++++++++++++++++-------------- 1 file changed, 39 insertions(+), 20 deletions(-)