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| author | Alejandro Colomar <alx@kernel.org> | 2023-08-14 15:41:07 +0200 |
|---|---|---|
| committer | Alejandro Colomar <alx@kernel.org> | 2023-08-15 23:07:10 +0200 |
| commit | b47bcfdd986ea41da74c2b58d09d14bf28cda756 (patch) | |
| tree | dfa91514ffbd09e0c42cc904c627899425cf7962 /man5/proc.5 | |
| parent | a011a2454cf641d24869626d905affb1c4e5adfc (diff) | |
| download | man-pages-b47bcfdd986ea41da74c2b58d09d14bf28cda756.tar.gz | |
proc.5, proc_pid_io.5: Split /proc/PID/io from proc(5)
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Diffstat (limited to 'man5/proc.5')
| -rw-r--r-- | man5/proc.5 | 86 |
1 files changed, 0 insertions, 86 deletions
diff --git a/man5/proc.5 b/man5/proc.5 index d3b762c74f..c931cea645 100644 --- a/man5/proc.5 +++ b/man5/proc.5 @@ -267,92 +267,6 @@ Therefore, it may be desirable to reset the "dumpable" attribute .I after making any desired changes to the process's effective UID or GID. .TP -.IR /proc/ pid /io " (since Linux 2.6.20)" -.\" commit 7c3ab7381e79dfc7db14a67c6f4f3285664e1ec2 -This file contains I/O statistics for the process, for example: -.IP -.in +4n -.EX -.RB "#" " cat /proc/3828/io" -rchar: 323934931 -wchar: 323929600 -syscr: 632687 -syscw: 632675 -read_bytes: 0 -write_bytes: 323932160 -cancelled_write_bytes: 0 -.EE -.in -.IP -The fields are as follows: -.RS -.TP -.IR rchar ": characters read" -The number of bytes which this task has caused to be read from storage. -This is simply the sum of bytes which this process passed to -.BR read (2) -and similar system calls. -It includes things such as terminal I/O and -is unaffected by whether or not actual -physical disk I/O was required (the read might have been satisfied from -pagecache). -.TP -.IR wchar ": characters written" -The number of bytes which this task has caused, or shall cause to be written -to disk. -Similar caveats apply here as with -.IR rchar . -.TP -.IR syscr ": read syscalls" -Attempt to count the number of read I/O operations\[em]that is, -system calls such as -.BR read (2) -and -.BR pread (2). -.TP -.IR syscw ": write syscalls" -Attempt to count the number of write I/O operations\[em]that is, -system calls such as -.BR write (2) -and -.BR pwrite (2). -.TP -.IR read_bytes ": bytes read" -Attempt to count the number of bytes which this process really did cause to -be fetched from the storage layer. -This is accurate for block-backed filesystems. -.TP -.IR write_bytes ": bytes written" -Attempt to count the number of bytes which this process caused to be sent to -the storage layer. -.TP -.IR cancelled_write_bytes : -The big inaccuracy here is truncate. -If a process writes 1 MB to a file and then deletes the file, -it will in fact perform no writeout. -But it will have been accounted as having caused 1 MB of write. -In other words: this field represents the number of bytes which this process -caused to not happen, by truncating pagecache. -A task can cause "negative" I/O too. -If this task truncates some dirty pagecache, -some I/O which another task has been accounted for -(in its -.IR write_bytes ) -will not be happening. -.RE -.IP -.IR Note : -In the current implementation, things are a bit racy on 32-bit systems: -if process A reads process B's -.IR /proc/ pid /io -while process B is updating one of these 64-bit counters, -process A could see an intermediate result. -.IP -Permission to access this file is governed by a ptrace access mode -.B PTRACE_MODE_READ_FSCREDS -check; see -.BR ptrace (2). -.TP .IR /proc/ pid /limits " (since Linux 2.6.24)" This file displays the soft limit, hard limit, and units of measurement for each of the process's resource limits (see |