mirror of
https://github.com/git/git
synced 2024-08-27 11:39:22 +00:00
grep: use no. of cores as the default no. of threads
When --threads is not specified, git-grep will use 8 threads by default. This fixed number may be too many for machines with fewer cores and too little for machines with more cores. So, instead, use the number of logical cores available in the machine, which seems to result in the best overall performance: The following measurements correspond to the mean elapsed times for 30 git-grep executions in chromium's repository[1] with a 95% confidence interval (each set of 30 were performed after 2 warmup runs). Regex 1 is 'abcd[02]' and Regex 2 is '(static|extern) (int|double) \*'. | Working tree | Object Store ------|-------------------------------|-------------------------------- #ths | Regex 1 | Regex 2 | Regex 1 | Regex 2 ------|---------------|---------------|----------------|--------------- 32 | 2.92s ± 0.01 | 3.72s ± 0.21 | 5.36s ± 0.01 | 6.07s ± 0.01 16 | 2.84s ± 0.01 | 3.57s ± 0.21 | 5.05s ± 0.01 | 5.71s ± 0.01 > 8 | 2.53s ± 0.00 | 3.24s ± 0.21 | 4.86s ± 0.01 | 5.48s ± 0.01 4 | 2.43s ± 0.02 | 3.22s ± 0.20 | 5.22s ± 0.02 | 6.03s ± 0.02 2 | 3.06s ± 0.20 | 4.52s ± 0.01 | 7.52s ± 0.01 | 9.06s ± 0.01 1 | 6.16s ± 0.01 | 9.25s ± 0.02 | 14.10s ± 0.01 | 17.22s ± 0.01 The above tests were performed in a desktop running Debian 10.0 with Intel(R) Xeon(R) CPU E3-1230 V2 (4 cores w/ hyper-threading), 32GB of RAM and a 7200 rpm, SATA 3.1 HDD. Bellow, the tests were repeated for a machine with SSD: a Manjaro laptop with Intel(R) i7-7700HQ (4 cores w/ hyper-threading) and 16GB of RAM: | Working tree | Object Store ------|--------------------------------|-------------------------------- #ths | Regex 1 | Regex 2 | Regex 1 | Regex 2 ------|---------------|----------------|----------------|--------------- 32 | 3.29s ± 0.21 | 4.30s ± 0.01 | 6.30s ± 0.01 | 7.30s ± 0.02 16 | 3.19s ± 0.20 | 4.14s ± 0.02 | 5.91s ± 0.01 | 6.83s ± 0.01 > 8 | 2.90s ± 0.04 | 3.82s ± 0.20 | 5.70s ± 0.02 | 6.53s ± 0.01 4 | 2.84s ± 0.02 | 3.77s ± 0.20 | 6.19s ± 0.02 | 7.18s ± 0.02 2 | 3.73s ± 0.21 | 5.57s ± 0.02 | 9.28s ± 0.01 | 11.22s ± 0.01 1 | 7.48s ± 0.02 | 11.36s ± 0.03 | 17.75s ± 0.01 | 21.87s ± 0.08 [1]: chromium’s repo at commit 03ae96f (“Add filters testing at DSF=2”, 04-06-2019), after a 'git gc' execution. Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br> Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
parent
70a9fef240
commit
f1928f04b2
|
@ -59,8 +59,8 @@ grep.extendedRegexp::
|
|||
other than 'default'.
|
||||
|
||||
grep.threads::
|
||||
Number of grep worker threads to use. If unset (or set to 0),
|
||||
8 threads are used by default (for now).
|
||||
Number of grep worker threads to use. If unset (or set to 0), Git will
|
||||
use as many threads as the number of logical cores available.
|
||||
|
||||
grep.fullName::
|
||||
If set to true, enable `--full-name` option by default.
|
||||
|
|
|
@ -33,7 +33,6 @@ static char const * const grep_usage[] = {
|
|||
|
||||
static int recurse_submodules;
|
||||
|
||||
#define GREP_NUM_THREADS_DEFAULT 8
|
||||
static int num_threads;
|
||||
|
||||
static pthread_t *threads;
|
||||
|
@ -1064,7 +1063,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
|
|||
} else if (num_threads < 0)
|
||||
die(_("invalid number of threads specified (%d)"), num_threads);
|
||||
else if (num_threads == 0)
|
||||
num_threads = HAVE_THREADS ? GREP_NUM_THREADS_DEFAULT : 1;
|
||||
num_threads = HAVE_THREADS ? online_cpus() : 1;
|
||||
|
||||
if (num_threads > 1) {
|
||||
if (!HAVE_THREADS)
|
||||
|
|
Loading…
Reference in a new issue