pgcacher is used to get page cache statistics for files. Use the pgcacher command to know how much cache space the fd of the specified process occupies in the page cache. Use pgcacher to know whether the specified file list is cached in the page cache, and how much space is cached.
Compared with pcstat, pgcacher has fixed the problem that the file list of the process is incorrect. It used to be obtained through /proc/{pid}/maps, but now it is changed to obtain from /proc/{pid}/maps and /proc/{pid}/fd at the same time. pgcacher supports more parameters, such as top, worker, limit, depth, least-size, exclude-files and include-files. π
In addition, the pgcacher code is more robust, and also supports concurrency parameters, which can calculate the cache occupancy in the page cache faster.
π pgcacher has better performance than pcstat, and the performance gap becomes more obvious as the number of files increases. Can be up to 5x faster than pcstat for most scenarios.
the some code of
pkg/pcstatscopy from pcstat and hcache.
pgcacher <-json <-pps>|-terse|-default> <-nohdr> <-bname> file file file
-limit limit the number of files displayed, default: 500
-depth set the depth of dirs to scan, default: 0
-worker concurrency workers, default: 2
-pid show all open maps for the given pid
-top scan the open files of all processes, show the top few files that occupy the most memory space in the page cache, default: false
-lease-size ignore files smaller than the lastSize, such as '10MB' and '15GB'
-exclude-files exclude the specified files by wildcard, such as 'a*c?d' and '*xiaorui*,rfyiamcool'
-include-files only include the specified files by wildcard, such as 'a*c?d' and '*xiaorui?cc,rfyiamcool'
-json output will be JSON
-pps include the per-page information in the output (can be huge!)
-terse print terse machine-parseable output
-histo print a histogram using unicode block characters
-nohdr don't print the column header in terse or default format
-bname use basename(file) in the output (use for long paths)
-plain return data with no box characters
-unicode return data with unicode box charactersgit clone https://github.com/rfyiamcool/pgcacher.git
cd pgcacher
make build
sudo cp pgcacher /usr/local/bin/
pgcacher -hhttps://github.com/rfyiamcool/pgcacher/releases
- download package from github releases url.
- decompress the package.
- copy
pgcacherto/usr/local/bin.
test pass on ubuntu, centos 7.x and centos 8.x.
wget xiaorui-cc.oss-cn-hangzhou.aliyuncs.com/files/pgcacher
chmod 777 pgcacher
\cp pgcacher /usr/local/bin
# sudo pgcacher -pid=29260 -worker=5
+-------------------+----------------+-------------+----------------+-------------+---------+
| Name | Size β Pages β Cached Size β Cached Pagesβ Percent β
|-------------------+----------------+-------------+----------------+-------------+---------|
| /root/rui/file4g | 3.906G | 1024000 | 3.906G | 1024000 | 100.000 |
| /root/rui/file3g | 2.930G | 768000 | 2.930G | 768000 | 100.000 |
| /root/rui/file2g | 1.953G | 512000 | 1.953G | 512000 | 100.000 |
| /root/rui/file1g | 1000.000M | 256000 | 1000.000M | 256000 | 100.000 |
| /root/rui/open_re | 1.791M | 459 | 1.791M | 459 | 100.000 |
|-------------------+----------------+-------------+----------------+-------------+---------|
β Sum β 9.767G β 2560459 β 9.767G β 2560459 β 100.000 β
+-------------------+----------------+-------------+----------------+-------------+---------+
# dd if=/dev/urandom of=file1g bs=1M count=1000
# dd if=/dev/urandom of=file2g bs=1M count=2000
# dd if=/dev/urandom of=file3g bs=1M count=3000
# dd if=/dev/urandom of=file4g bs=1M count=4000
# cat file1g file2g file3g file4g > /dev/null
# sudo pgcacher file1g file2g file3g file4g
+--------+----------------+-------------+----------------+-------------+---------+
| Name | Size β Pages β Cached Size β Cached Pagesβ Percent β
|--------+----------------+-------------+----------------+-------------+---------|
| file4g | 3.906G | 1024000 | 3.906G | 1024000 | 100.000 |
| file3g | 2.930G | 768000 | 2.930G | 768000 | 100.000 |
| file2g | 1.953G | 512000 | 1.953G | 512000 | 100.000 |
| file1g | 1000.000M | 256000 | 1000.000M | 256000 | 100.000 |
|--------+----------------+-------------+----------------+-------------+---------|
β Sum β 9.766G β 2560000 β 9.766G β 2560000 β 100.000 β
+--------+----------------+-------------+----------------+-------------+---------+
# sudo pgcacher /root/rui/*
+------------+----------------+-------------+----------------+-------------+---------+
| Name | Size β Pages β Cached Size β Cached Pagesβ Percent β
|------------+----------------+-------------+----------------+-------------+---------|
| file4g | 3.906G | 1024000 | 3.906G | 1024000 | 100.000 |
| file3g | 2.930G | 768000 | 2.930G | 768000 | 100.000 |
| file2g | 1.953G | 512000 | 1.953G | 512000 | 100.000 |
| testfile | 1000.000M | 256000 | 1000.000M | 256000 | 100.000 |
| file1g | 1000.000M | 256000 | 1000.000M | 256000 | 100.000 |
| pgcacher | 2.440M | 625 | 2.440M | 625 | 100.000 |
| open_re | 1.791M | 459 | 1.791M | 459 | 100.000 |
| cache.go | 19.576K | 5 | 19.576K | 5 | 100.000 |
| open_re.go | 644B | 1 | 644B | 1 | 100.000 |
| nohup.out | 957B | 1 | 957B | 1 | 100.000 |
|------------+----------------+-------------+----------------+-------------+---------|
β Sum β 10.746G β 2817091 β 10.746G β 2817091 β 100.000 β
+------------+----------------+-------------+----------------+-------------+---------+
# sudo pgcacher -top -limit 3
+------------------+----------------+-------------+----------------+-------------+---------+
| Name | Size β Pages β Cached Size β Cached Pagesβ Percent β
|------------------+----------------+-------------+----------------+-------------+---------|
| /root/rui/file4g | 3.906G | 1024000 | 3.906G | 1024000 | 100.000 |
| /root/rui/file3g | 2.930G | 768000 | 2.930G | 768000 | 100.000 |
| /root/rui/file2g | 1.953G | 512000 | 1.953G | 512000 | 100.000 |
|------------------+----------------+-------------+----------------+-------------+---------|
β Sum β 8.789G β 2304000 β 8.789G β 2304000 β 100.000 β
+------------------+----------------+-------------+----------------+-------------+---------+
# sudo pgcacher -depth=4 aaa/
+---------------------+----------------+-------------+----------------+-------------+---------+
| Name | Size β Pages β Cached Size β Cached Pagesβ Percent β
|---------------------+----------------+-------------+----------------+-------------+---------|
| aaa/a2g | 1.953G | 512000 | 1.953G | 512000 | 100.000 |
| aaa/bbb/ccc/ddd/d2g | 1.953G | 512000 | 1.940G | 508531 | 99.322 |
| aaa/bbb/ccc/c1g | 1000.000M | 256000 | 1000.000M | 256000 | 100.000 |
| aaa/bbb/ccc/c2g | 1.953G | 512000 | 1000.000M | 256000 | 50.000 |
| aaa/bbb/ccc/ddd/d1g | 1000.000M | 256000 | 1000.000M | 256000 | 100.000 |
| aaa/a1g | 1000.000M | 256000 | 1000.000M | 256000 | 100.000 |
| aaa/bbb/bbb1g | 1000.000M | 256000 | 1000.000M | 256000 | 100.000 |
| aaa/bbb/bbb2g | 1.953G | 512000 | 1000.000M | 256000 | 50.000 |
|---------------------+----------------+-------------+----------------+-------------+---------|
β Sum β 11.719G β 3072000 β 9.752G β 2556531 β 83.220 β
+---------------------+----------------+-------------+----------------+-------------+---------+
@tobert for pcstat