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| author | Kuniyuki Iwashima <kuniyu@amazon.com> | 2024-01-23 20:08:56 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2024-01-27 07:34:25 +0300 |
| commit | d9f21b3613337b55cc9d4a6ead484dca68475143 (patch) | |
| tree | 4345fae53e80824da6164e33c5f2577ffb92616d /include/net/af_unix.h | |
| parent | 8b90a9f819dc2a06baae4ec1a64d875e53b824ec (diff) | |
| download | linux-d9f21b3613337b55cc9d4a6ead484dca68475143.tar.xz | |
af_unix: Try to run GC async.
If more than 16000 inflight AF_UNIX sockets exist and the garbage
collector is not running, unix_(dgram|stream)_sendmsg() call unix_gc().
Also, they wait for unix_gc() to complete.
In unix_gc(), all inflight AF_UNIX sockets are traversed at least once,
and more if they are the GC candidate. Thus, sendmsg() significantly
slows down with too many inflight AF_UNIX sockets.
However, if a process sends data with no AF_UNIX FD, the sendmsg() call
does not need to wait for GC. After this change, only the process that
meets the condition below will be blocked under such a situation.
1) cmsg contains AF_UNIX socket
2) more than 32 AF_UNIX sent by the same user are still inflight
Note that even a sendmsg() call that does not meet the condition but has
AF_UNIX FD will be blocked later in unix_scm_to_skb() by the spinlock,
but we allow that as a bonus for sane users.
The results below are the time spent in unix_dgram_sendmsg() sending 1
byte of data with no FD 4096 times on a host where 32K inflight AF_UNIX
sockets exist.
Without series: the sane sendmsg() needs to wait gc unreasonably.
$ sudo /usr/share/bcc/tools/funclatency -p 11165 unix_dgram_sendmsg
Tracing 1 functions for "unix_dgram_sendmsg"... Hit Ctrl-C to end.
^C
nsecs : count distribution
[...]
524288 -> 1048575 : 0 | |
1048576 -> 2097151 : 3881 |****************************************|
2097152 -> 4194303 : 214 |** |
4194304 -> 8388607 : 1 | |
avg = 1825567 nsecs, total: 7477526027 nsecs, count: 4096
With series: the sane sendmsg() can finish much faster.
$ sudo /usr/share/bcc/tools/funclatency -p 8702 unix_dgram_sendmsg
Tracing 1 functions for "unix_dgram_sendmsg"... Hit Ctrl-C to end.
^C
nsecs : count distribution
[...]
128 -> 255 : 0 | |
256 -> 511 : 4092 |****************************************|
512 -> 1023 : 2 | |
1024 -> 2047 : 0 | |
2048 -> 4095 : 0 | |
4096 -> 8191 : 1 | |
8192 -> 16383 : 1 | |
avg = 410 nsecs, total: 1680510 nsecs, count: 4096
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240123170856.41348-6-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include/net/af_unix.h')
| -rw-r--r-- | include/net/af_unix.h | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/include/net/af_unix.h b/include/net/af_unix.h index 2c98ef95017b..f045bbd9017d 100644 --- a/include/net/af_unix.h +++ b/include/net/af_unix.h @@ -8,13 +8,21 @@ #include <linux/refcount.h> #include <net/sock.h> +#if IS_ENABLED(CONFIG_UNIX) +struct unix_sock *unix_get_socket(struct file *filp); +#else +static inline struct unix_sock *unix_get_socket(struct file *filp) +{ + return NULL; +} +#endif + void unix_inflight(struct user_struct *user, struct file *fp); void unix_notinflight(struct user_struct *user, struct file *fp); void unix_destruct_scm(struct sk_buff *skb); void io_uring_destruct_scm(struct sk_buff *skb); void unix_gc(void); -void wait_for_unix_gc(void); -struct unix_sock *unix_get_socket(struct file *filp); +void wait_for_unix_gc(struct scm_fp_list *fpl); struct sock *unix_peer_get(struct sock *sk); #define UNIX_HASH_MOD (256 - 1) |