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sockets: c/r bufer size locks

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When one sets socket buffer sizes with setsockopt(SO_{SND,RCV}BUF*),
kernel sets coresponding SOCK_SNDBUF_LOCK or SOCK_RCVBUF_LOCK flags on
struct sock. It means that such a socket with explicitly changed buffer
size can not be auto-adjusted by kernel (e.g. if there is free memory
kernel can auto-increase default socket buffers to improve perfomance).
(see tcp_fixup_rcvbuf() and tcp_sndbuf_expand())

CRIU is always changing buf sizes on restore, that means that all
sockets receive lock flags on struct sock and become non-auto-adjusted
after migration. In some cases it can decrease perfomance of network
connections quite a lot.

So let's c/r socket buf locks (SO_BUF_LOCKS), so that sockets for which
auto-adjustment is available does not lose it.

Reviewed-by: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>
Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
This commit is contained in:
Pavel Tikhomirov 2021-07-29 11:27:13 +03:00 • committed by Andrei Vagin
parent ce5ce285a8
commit e69be16db7
2 changed files with 10 additions and 0 deletions
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8
criu/sockets.c
View file

@ -519,6 +519,10 @@ int restore_socket_opts(int sk, SkOptsEntry *soe)
/* setsockopt() multiplies the input values by 2 */
ret |= userns_call(sk_setbufs, 0, bufs, sizeof(bufs), sk);
if (soe->has_so_buf_lock) {
pr_debug("\trestore buf_lock %d for socket\n", soe->so_buf_lock);
ret |= restore_opt(sk, SOL_SOCKET, SO_BUF_LOCK, &soe->so_buf_lock);
}
if (soe->has_so_priority) {
pr_debug("\trestore priority %d for socket\n", soe->so_priority);
ret |= restore_opt(sk, SOL_SOCKET, SO_PRIORITY, &soe->so_priority);
@ -619,6 +623,10 @@ int dump_socket_opts(int sk, SkOptsEntry *soe)
ret |= dump_opt(sk, SOL_SOCKET, SO_SNDBUF, &soe->so_sndbuf);
ret |= dump_opt(sk, SOL_SOCKET, SO_RCVBUF, &soe->so_rcvbuf);
if (kdat.has_sockopt_buf_lock) {
soe->has_so_buf_lock = true;
ret |= dump_opt(sk, SOL_SOCKET, SO_BUF_LOCK, &soe->so_buf_lock);
}
soe->has_so_priority = true;
ret |= dump_opt(sk, SOL_SOCKET, SO_PRIORITY, &soe->so_priority);
soe->has_so_rcvlowat = true;

2
images/sk-opts.proto
View file

@ -31,6 +31,8 @@ message sk_opts_entry {
optional uint32 tcp_keepintvl = 22;
optional uint32 so_oobinline = 23;
optional uint32 so_linger = 24;
optional uint32 so_buf_lock = 25;
}
enum sk_shutdown {