new file mode 100755
@@ -0,0 +1,257 @@
+#!/bin/sh
+
+test_description="Perf test for the builtin FSMonitor"
+
+. ./perf-lib.sh
+
+if ! test_have_prereq FSMONITOR_DAEMON
+then
+ skip_all="fsmonitor--daemon is not supported on this platform"
+ test_done
+fi
+
+test_lazy_prereq UNTRACKED_CACHE '
+ { git update-index --test-untracked-cache; ret=$?; } &&
+ test $ret -ne 1
+'
+
+# Lie to perf-lib and ask for a new empty repo and avoid
+# the complaints about GIT_PERF_REPO not being big enough
+# the perf hit when GIT_PERF_LARGE_REPO is copied into
+# the trash directory.
+#
+# NEEDSWORK: It would be nice if perf-lib had an option to
+# "borrow" an existing large repo (especially for gigantic
+# monorepos) and use it in-place. For now, fake it here.
+#
+test_perf_fresh_repo
+
+
+# Use a generated synthetic monorepo. If it doesn't exist, we will
+# generate it. If it does exist, we will put it in a known state
+# before we start our timings.
+#
+PARAM_D=5
+PARAM_W=10
+PARAM_F=9
+
+PARAMS="$PARAM_D"."$PARAM_W"."$PARAM_F"
+
+BALLAST_BR=p0006-ballast
+export BALLAST_BR
+
+TMP_BR=tmp_br
+export TMP_BR
+
+REPO=../repos/gen-many-files-"$PARAMS".git
+export REPO
+
+if ! test -d $REPO
+then
+ (cd ../repos; ./many-files.sh -d $PARAM_D -w $PARAM_W -f $PARAM_F)
+fi
+
+
+enable_uc () {
+ git -C $REPO config core.untrackedcache true
+ git -C $REPO update-index --untracked-cache
+ git -C $REPO status >/dev/null 2>&1
+}
+
+disable_uc () {
+ git -C $REPO config core.untrackedcache false
+ git -C $REPO update-index --no-untracked-cache
+ git -C $REPO status >/dev/null 2>&1
+}
+
+start_fsm () {
+ git -C $REPO fsmonitor--daemon start
+ git -C $REPO fsmonitor--daemon status
+ git -C $REPO config core.fsmonitor true
+ git -C $REPO update-index --fsmonitor
+ git -C $REPO status >/dev/null 2>&1
+}
+
+stop_fsm () {
+ git -C $REPO config --unset core.fsmonitor
+ git -C $REPO update-index --no-fsmonitor
+ test_might_fail git -C $REPO fsmonitor--daemon stop 2>/dev/null
+ git -C $REPO status >/dev/null 2>&1
+}
+
+
+# Ensure that FSMonitor is turned off on the borrowed repo.
+#
+test_expect_success "Setup borrowed repo (fsm+uc)" "
+ stop_fsm &&
+ disable_uc
+"
+
+# Also ensure that it starts in a known state.
+#
+# Because we assume that $GIT_PERF_REPEAT_COUNT > 1, we are not going to time
+# the ballast checkout, since only the first invocation does any work and the
+# subsequent ones just print "already on branch" and quit, so the reported
+# time is not useful.
+#
+# Create a temp branch and do all work relative to it so that we don't
+# accidentially alter the real ballast branch.
+#
+test_expect_success "Setup borrowed repo (temp ballast branch)" "
+ test_might_fail git -C $REPO checkout $BALLAST_BR &&
+ test_might_fail git -C $REPO reset --hard &&
+ git -C $REPO clean -d -f &&
+ test_might_fail git -C $REPO branch -D $TMP_BR &&
+ git -C $REPO branch $TMP_BR $BALLAST_BR &&
+ git -C $REPO checkout $TMP_BR
+"
+
+
+echo Data >data.txt
+
+# NEEDSWORK: We assume that $GIT_PERF_REPEAT_COUNT > 1. With
+# FSMonitor enabled, we can get a skewed view of status times, since
+# the index MAY (or may not) be updated after the first invocation
+# which will update the FSMonitor Token, so the subsequent invocations
+# may get a smaller response from the daemon.
+#
+do_status () {
+ msg=$1
+
+ test_perf "$msg" "
+ git -C $REPO status >/dev/null 2>&1
+ "
+}
+
+do_matrix () {
+ uc=$1
+ fsm=$2
+
+ t="[uc $uc][fsm $fsm]"
+ MATRIX_BR="$TMP_BR-$uc-$fsm"
+
+ test_expect_success "$t Setup matrix branch" "
+ git -C $REPO clean -d -f &&
+ git -C $REPO checkout $TMP_BR &&
+ test_might_fail git -C $REPO branch -D $MATRIX_BR &&
+ git -C $REPO branch $MATRIX_BR $TMP_BR &&
+ git -C $REPO checkout $MATRIX_BR
+ "
+
+ if test $uc = true
+ then
+ enable_uc
+ else
+ disable_uc
+ fi
+
+ if test $fsm = true
+ then
+ start_fsm
+ else
+ stop_fsm
+ fi
+
+ do_status "$t status after checkout"
+
+ # Modify many files in the matrix branch.
+ # Stage them.
+ # Commit them.
+ # Rollback.
+ #
+ test_expect_success "$t modify tracked files" "
+ find $REPO -name file1 -exec cp data.txt {} \\;
+ "
+
+ do_status "$t status after big change"
+
+ # Don't bother timing the "add" because _REPEAT_COUNT
+ # issue described above.
+ #
+ test_expect_success "$t add all" "
+ git -C $REPO add -A
+ "
+
+ do_status "$t status after add all"
+
+ test_expect_success "$t add dot" "
+ git -C $REPO add .
+ "
+
+ do_status "$t status after add dot"
+
+ test_expect_success "$t commit staged" "
+ git -C $REPO commit -a -m data
+ "
+
+ do_status "$t status after commit"
+
+ test_expect_success "$t reset HEAD~1 hard" "
+ git -C $REPO reset --hard HEAD~1 >/dev/null 2>&1
+ "
+
+ do_status "$t status after reset hard"
+
+ # Create some untracked files.
+ #
+ test_expect_success "$t create untracked files" "
+ cp -R $REPO/ballast/dir1 $REPO/ballast/xxx1
+ "
+
+ do_status "$t status after create untracked files"
+
+ # Remove the new untracked files.
+ #
+ test_expect_success "$t clean -df" "
+ git -C $REPO clean -d -f
+ "
+
+ do_status "$t status after clean"
+
+ if test $fsm = true
+ then
+ stop_fsm
+ fi
+}
+
+# Begin testing each case in the matrix that we care about.
+#
+uc_values="false"
+test_have_prereq UNTRACKED_CACHE && uc_values="false true"
+
+fsm_values="false true"
+
+for uc_val in $uc_values
+do
+ for fsm_val in $fsm_values
+ do
+ do_matrix $uc_val $fsm_val
+ done
+done
+
+cleanup () {
+ uc=$1
+ fsm=$2
+
+ MATRIX_BR="$TMP_BR-$uc-$fsm"
+
+ test_might_fail git -C $REPO branch -D $MATRIX_BR
+}
+
+
+# We're borrowing this repo. We should leave it in a clean state.
+#
+test_expect_success "Cleanup temp and matrix branches" "
+ git -C $REPO clean -d -f &&
+ test_might_fail git -C $REPO checkout $BALLAST_BR &&
+ test_might_fail git -C $REPO branch -D $TMP_BR &&
+ for uc_val in $uc_values
+ do
+ for fsm_val in $fsm_values
+ do
+ cleanup $uc_val $fsm_val
+ done
+ done
+"
+
+test_done