"core.fsync" and the "GIT_FSYNC" environment variable now exist
for disabling fsync() even on packfiles and other critical data.
Running "make test -j8 NO_SVN_TESTS=1" on a noisy 8-core system
on an HDD, adding "GIT_FSYNC=0" to the invocation brings my test
runtime from ~4 minutes down to ~3 minutes.
SVN interopability tests are minimally affected since SVN will
still use fsync in various places.
This will also be useful for 3rd-party tools which create
throwaway git repositories of temporary data.
Signed-off-by: Eric Wong <e@xxxxxxxxx>
---
Documentation/config/core.txt | 7 +++++++
Documentation/git.txt | 5 +++++
cache.h | 1 +
config.c | 5 +++++
environment.c | 1 +
git-cvsserver.perl | 22 ++++++++++++++++++++++
perl/Git/SVN.pm | 20 ++++++++++++++++++--
t/test-lib.sh | 1 +
write-or-die.c | 5 ++++-
9 files changed, 64 insertions(+), 3 deletions(-)
diff --git a/Documentation/config/core.txt b/Documentation/config/core.txt
index c04f62a54a..2ad5364246 100644
--- a/Documentation/config/core.txt
+++ b/Documentation/config/core.txt
@@ -555,6 +555,13 @@ data writes properly, but can be useful for filesystems that do not use
journalling (traditional UNIX filesystems) or that only journal metadata
and not file contents (OS X's HFS+, or Linux ext3 with "data=writeback").
+core.fsync::
+ A boolean to control 'fsync()' on all files.
++
+Setting this to false can speed up writes of unimportant data.
+Disabling fsync will lead to data loss on power failure. If set
+to false, this also overrides core.fsyncObjectFiles. Defaults to true.
+
core.preloadIndex::
Enable parallel index preload for operations like 'git diff'
+
diff --git a/Documentation/git.txt b/Documentation/git.txt
index d63c65e67d..cda4504e41 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -703,6 +703,11 @@ for further details.
not set, Git will choose buffered or record-oriented flushing
based on whether stdout appears to be redirected to a file or not.
+`GIT_FSYNC`::
+ Setting this environment variable to "0" disables fsync() entirely.
+ This is intended for running test suites and other repositories of
+ unimportant data. See also core.fsync in linkgit:git-config[1].
+
`GIT_TRACE`::
Enables general trace messages, e.g. alias expansion, built-in
command execution and external command execution.
diff --git a/cache.h b/cache.h
index eba12487b9..de6c45cf44 100644
--- a/cache.h
+++ b/cache.h
@@ -986,6 +986,7 @@ extern int read_replace_refs;
extern char *git_replace_ref_base;
extern int fsync_object_files;
+extern int use_fsync;
extern int core_preload_index;
extern int precomposed_unicode;
extern int protect_hfs;
diff --git a/config.c b/config.c
index 2dcbe901b6..1ea7cb801b 100644
--- a/config.c
+++ b/config.c
@@ -1492,6 +1492,11 @@ static int git_default_core_config(const char *var, const char *value, void *cb)
return 0;
}
+ if (!strcmp(var, "core.fsync")) {
+ use_fsync = git_config_bool(var, value);
+ return 0;
+ }
+
if (!strcmp(var, "core.preloadindex")) {
core_preload_index = git_config_bool(var, value);
return 0;
diff --git a/environment.c b/environment.c
index 9da7f3c1a1..0d06a31024 100644
--- a/environment.c
+++ b/environment.c
@@ -42,6 +42,7 @@ const char *git_hooks_path;
int zlib_compression_level = Z_BEST_SPEED;
int pack_compression_level = Z_DEFAULT_COMPRESSION;
int fsync_object_files;
+int use_fsync = -1;
size_t packed_git_window_size = DEFAULT_PACKED_GIT_WINDOW_SIZE;
size_t packed_git_limit = DEFAULT_PACKED_GIT_LIMIT;
size_t delta_base_cache_limit = 96 * 1024 * 1024;
diff --git a/git-cvsserver.perl b/git-cvsserver.perl
index 64319bed43..7679819e4d 100755
--- a/git-cvsserver.perl
+++ b/git-cvsserver.perl
@@ -3607,6 +3607,25 @@ package GITCVS::updater;
use strict;
use warnings;
use DBI;
+our $_use_fsync;
+
+# n.b. consider using Git.pm
+sub use_fsync {
+ if (!defined($_use_fsync)) {
+ my $x = $ENV{GIT_FSYNC};
+ if (defined $x) {
+ local $ENV{GIT_CONFIG};
+ delete $ENV{GIT_CONFIG};
+ my $v = ::safe_pipe_capture('git', '-c', "core.fsync=$x",
+ qw(config --type=bool core.fsync));
+ $_use_fsync = defined($v) ? ($v eq "true\n") : 1;
+ } else {
+ my $v = `git config --type=bool core.fsync`;
+ $_use_fsync = $v eq "false\n" ? 0 : 1;
+ }
+ }
+ $_use_fsync;
+}
=head1 METHODS
@@ -3676,6 +3695,9 @@ sub new
$self->{dbuser},
$self->{dbpass});
die "Error connecting to database\n" unless defined $self->{dbh};
+ if ($self->{dbdriver} eq 'SQLite' && !use_fsync()) {
+ $self->{dbh}->do('PRAGMA synchronous = OFF');
+ }
$self->{tables} = {};
foreach my $table ( keys %{$self->{dbh}->table_info(undef,undef,undef,'TABLE')->fetchall_hashref('TABLE_NAME')} )
diff --git a/perl/Git/SVN.pm b/perl/Git/SVN.pm
index 35ff5a6896..7b333ea62e 100644
--- a/perl/Git/SVN.pm
+++ b/perl/Git/SVN.pm
@@ -6,7 +6,7 @@ package Git::SVN;
use vars qw/$_no_metadata
$_repack $_repack_flags $_use_svm_props $_head
$_use_svnsync_props $no_reuse_existing
- $_use_log_author $_add_author_from $_localtime/;
+ $_use_log_author $_add_author_from $_localtime $_use_fsync/;
use Carp qw/croak/;
use File::Path qw/mkpath/;
use IPC::Open3;
@@ -2269,6 +2269,22 @@ sub mkfile {
}
}
+# TODO: move this to Git.pm?
+sub use_fsync {
+ if (!defined($_use_fsync)) {
+ my $x = $ENV{GIT_FSYNC};
+ if (defined $x) {
+ my $v = command_oneline('git', '-c', "core.fsync=$x",
+ qw(config --type=bool core.fsync));
+ $_use_fsync = defined($v) ? ($v eq "true\n") : 1;
+ } else {
+ $_use_fsync = Git::config_bool('core.fsync');
+ $_use_fsync = 1 if !defined($_use_fsync);
+ }
+ }
+ $_use_fsync;
+}
+
sub rev_map_set {
my ($self, $rev, $commit, $update_ref, $uuid) = @_;
defined $commit or die "missing arg3\n";
@@ -2290,7 +2306,7 @@ sub rev_map_set {
my $sync;
# both of these options make our .rev_db file very, very important
# and we can't afford to lose it because rebuild() won't work
- if ($self->use_svm_props || $self->no_metadata) {
+ if (($self->use_svm_props || $self->no_metadata) && use_fsync()) {
require File::Copy;
$sync = 1;
File::Copy::copy($db, $db_lock) or die "rev_map_set(@_): ",
diff --git a/t/test-lib.sh b/t/test-lib.sh
index a291a5d4a2..61bb24444c 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -442,6 +442,7 @@ unset VISUAL EMAIL LANGUAGE $("$PERL_PATH" -e '
PERF_
CURL_VERBOSE
TRACE_CURL
+ FSYNC
));
my @vars = grep(/^GIT_/ && !/^GIT_($ok)/o, @env);
print join("\n", @vars);
diff --git a/write-or-die.c b/write-or-die.c
index 0b1ec8190b..d2962dc423 100644
--- a/write-or-die.c
+++ b/write-or-die.c
@@ -1,4 +1,5 @@
#include "cache.h"
+#include "config.h"
#include "run-command.h"
/*
@@ -57,7 +58,9 @@ void fprintf_or_die(FILE *f, const char *fmt, ...)
void fsync_or_die(int fd, const char *msg)
{
- while (fsync(fd) < 0) {
+ if (use_fsync < 0)
+ use_fsync = git_env_bool("GIT_FSYNC", 1);
+ while (use_fsync && fsync(fd) < 0) {
if (errno != EINTR)
die_errno("fsync error on '%s'", msg);
}
