diff options
| author | Eric Dumazet <edumazet@google.com> | 2021-10-14 16:41:26 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-10-15 13:28:34 +0300 |
| commit | 19757cebf0c5016a1f36f7fe9810a9f0b33c0832 (patch) | |
| tree | 9d2349b63f328c9cb79fe6580215f823f8765b78 /drivers/net/ethernet/chelsio | |
| parent | 0b93aed2842d950e8d2625e975e5a57febeff33d (diff) | |
| download | linux-19757cebf0c5016a1f36f7fe9810a9f0b33c0832.tar.xz | |
tcp: switch orphan_count to bare per-cpu counters
Use of percpu_counter structure to track count of orphaned
sockets is causing problems on modern hosts with 256 cpus
or more.
Stefan Bach reported a serious spinlock contention in real workloads,
that I was able to reproduce with a netfilter rule dropping
incoming FIN packets.
53.56% server [kernel.kallsyms] [k] queued_spin_lock_slowpath
|
---queued_spin_lock_slowpath
|
--53.51%--_raw_spin_lock_irqsave
|
--53.51%--__percpu_counter_sum
tcp_check_oom
|
|--39.03%--__tcp_close
| tcp_close
| inet_release
| inet6_release
| sock_close
| __fput
| ____fput
| task_work_run
| exit_to_usermode_loop
| do_syscall_64
| entry_SYSCALL_64_after_hwframe
| __GI___libc_close
|
--14.48%--tcp_out_of_resources
tcp_write_timeout
tcp_retransmit_timer
tcp_write_timer_handler
tcp_write_timer
call_timer_fn
expire_timers
__run_timers
run_timer_softirq
__softirqentry_text_start
As explained in commit cf86a086a180 ("net/dst: use a smaller percpu_counter
batch for dst entries accounting"), default batch size is too big
for the default value of tcp_max_orphans (262144).
But even if we reduce batch sizes, there would still be cases
where the estimated count of orphans is beyond the limit,
and where tcp_too_many_orphans() has to call the expensive
percpu_counter_sum_positive().
One solution is to use plain per-cpu counters, and have
a timer to periodically refresh this cache.
Updating this cache every 100ms seems about right, tcp pressure
state is not radically changing over shorter periods.
percpu_counter was nice 15 years ago while hosts had less
than 16 cpus, not anymore by current standards.
v2: Fix the build issue for CONFIG_CRYPTO_DEV_CHELSIO_TLS=m,
reported by kernel test robot <lkp@intel.com>
Remove unused socket argument from tcp_too_many_orphans()
Fixes: dd24c00191d5 ("net: Use a percpu_counter for orphan_count")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Stefan Bach <sfb@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/chelsio')
| -rw-r--r-- | drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c | 2 | ||||
| -rw-r--r-- | drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.h | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c index bcad69c48074..4af5561cbfc5 100644 --- a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c +++ b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c @@ -870,7 +870,7 @@ static void do_abort_syn_rcv(struct sock *child, struct sock *parent) * created only after 3 way handshake is done. */ sock_orphan(child); - percpu_counter_inc((child)->sk_prot->orphan_count); + INC_ORPHAN_COUNT(child); chtls_release_resources(child); chtls_conn_done(child); } else { diff --git a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.h b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.h index b1161bdeda4d..f61ca657601c 100644 --- a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.h +++ b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.h @@ -95,7 +95,7 @@ struct deferred_skb_cb { #define WSCALE_OK(tp) ((tp)->rx_opt.wscale_ok) #define TSTAMP_OK(tp) ((tp)->rx_opt.tstamp_ok) #define SACK_OK(tp) ((tp)->rx_opt.sack_ok) -#define INC_ORPHAN_COUNT(sk) percpu_counter_inc((sk)->sk_prot->orphan_count) +#define INC_ORPHAN_COUNT(sk) this_cpu_inc(*(sk)->sk_prot->orphan_count) /* TLS SKB */ #define skb_ulp_tls_inline(skb) (ULP_SKB_CB(skb)->ulp.tls.ofld) |