122 lines
4.3 KiB
Markdown
122 lines
4.3 KiB
Markdown
# Filesystem Performance Benchmarking
|
|
|
|
Filesystem performance has a big impact on overall GitLab performance,
|
|
especially for actions that read or write to Git repositories. This information
|
|
will help benchmark filesystem performance against known good and bad real-world
|
|
systems.
|
|
|
|
Normally when talking about filesystem performance the biggest concern is
|
|
with Network Filesystems (NFS). However, even some local disks can have slow
|
|
I/O. The information on this page can be used for either scenario.
|
|
|
|
## Executing benchmarks
|
|
|
|
### Benchmarking with `fio`
|
|
|
|
We recommend using
|
|
[Fio](https://fio.readthedocs.io/en/latest/fio_doc.html) to test I/O
|
|
performance. This test should be run both on the NFS server and on the
|
|
application nodes that talk to the NFS server.
|
|
|
|
To install:
|
|
|
|
- On Ubuntu: `apt install fio`.
|
|
- On `yum`-managed environments: `yum install fio`.
|
|
|
|
Then run the following:
|
|
|
|
```shell
|
|
fio --randrepeat=1 --ioengine=libaio --direct=1 --gtod_reduce=1 --name=test --filename=/path/to/git-data/testfile --bs=4k --iodepth=64 --size=4G --readwrite=randrw --rwmixread=75
|
|
```
|
|
|
|
This will create a 4GB file in `/path/to/git-data/testfile`. It performs
|
|
4KB reads and writes using a 75%/25% split within the file, with 64
|
|
operations running at a time. Be sure to delete the file after the test
|
|
completes.
|
|
|
|
The output will vary depending on what version of `fio` installed. The following
|
|
is an example output from `fio` v2.2.10 on a networked solid-state drive (SSD):
|
|
|
|
```plaintext
|
|
test: (g=0): rw=randrw, bs=4K-4K/4K-4K/4K-4K, ioengine=libaio, iodepth=64
|
|
fio-2.2.10
|
|
Starting 1 process
|
|
test: Laying out IO file(s) (1 file(s) / 1024MB)
|
|
Jobs: 1 (f=1): [m(1)] [100.0% done] [131.4MB/44868KB/0KB /s] [33.7K/11.3K/0 iops] [eta 00m:00s]
|
|
test: (groupid=0, jobs=1): err= 0: pid=10287: Sat Feb 2 17:40:10 2019
|
|
read : io=784996KB, bw=133662KB/s, iops=33415, runt= 5873msec
|
|
write: io=263580KB, bw=44880KB/s, iops=11219, runt= 5873msec
|
|
cpu : usr=6.56%, sys=23.11%, ctx=266267, majf=0, minf=8
|
|
IO depths : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=0.1%, >=64=100.0%
|
|
submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
|
|
complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.1%, >=64=0.0%
|
|
issued : total=r=196249/w=65895/d=0, short=r=0/w=0/d=0, drop=r=0/w=0/d=0
|
|
latency : target=0, window=0, percentile=100.00%, depth=64
|
|
|
|
Run status group 0 (all jobs):
|
|
READ: io=784996KB, aggrb=133661KB/s, minb=133661KB/s, maxb=133661KB/s, mint=5873msec, maxt=5873msec
|
|
WRITE: io=263580KB, aggrb=44879KB/s, minb=44879KB/s, maxb=44879KB/s, mint=5873msec, maxt=5873msec
|
|
```
|
|
|
|
Notice the `iops` values in this output. In this example, the SSD
|
|
performed 33,415 read operations per second and 11,219 write operations
|
|
per second. A spinning disk might yield 2,000 and 700 read and write
|
|
operations per second.
|
|
|
|
### Simple benchmarking
|
|
|
|
NOTE: **Note:**
|
|
This test is naive but may be useful if `fio` is not
|
|
available on the system. It's possible to receive good results on this
|
|
test but still have poor performance due to read speed and various other
|
|
factors.
|
|
|
|
The following one-line commands provide a quick benchmark for filesystem write and read
|
|
performance. This will write 1,000 small files to the directory in which it is
|
|
executed, and then read the same 1,000 files.
|
|
|
|
1. Change into the root of the appropriate
|
|
[repository storage path](../repository_storage_paths.md).
|
|
1. Create a temporary directory for the test so it's easy to remove the files later:
|
|
|
|
```shell
|
|
mkdir test; cd test
|
|
```
|
|
|
|
1. Run the command:
|
|
|
|
```shell
|
|
time for i in {0..1000}; do echo 'test' > "test${i}.txt"; done
|
|
```
|
|
|
|
1. To benchmark read performance, run the command:
|
|
|
|
```shell
|
|
time for i in {0..1000}; do cat "test${i}.txt" > /dev/null; done
|
|
```
|
|
|
|
1. Remove the test files:
|
|
|
|
```shell
|
|
cd ../; rm -rf test
|
|
```
|
|
|
|
The output of the `time for ...` commands will look similar to the following. The
|
|
important metric is the `real` time.
|
|
|
|
```shell
|
|
$ time for i in {0..1000}; do echo 'test' > "test${i}.txt"; done
|
|
|
|
real 0m0.116s
|
|
user 0m0.025s
|
|
sys 0m0.091s
|
|
|
|
$ time for i in {0..1000}; do cat "test${i}.txt" > /dev/null; done
|
|
|
|
real 0m3.118s
|
|
user 0m1.267s
|
|
sys 0m1.663s
|
|
```
|
|
|
|
From experience with multiple customers, this task should take under 10
|
|
seconds to indicate good filesystem performance.
|