> On 1. Apr 2021, at 10:20, Marko Zec <z...@fer.hr> wrote: > > On Thu, 1 Apr 2021 08:03:57 GMT > Richard Scheffenegger <rsch...@freebsd.org> wrote: > >> The branch main has been updated by rscheff: >> >> URL: >> https://cgit.FreeBSD.org/src/commit/?id=529a2a0f2765f6c57c50a5af6be242c03bf714e3 >> >> commit 529a2a0f2765f6c57c50a5af6be242c03bf714e3 >> Author: Richard Scheffenegger <rsch...@freebsd.org> >> AuthorDate: 2021-04-01 08:00:32 +0000 >> Commit: Richard Scheffenegger <rsch...@freebsd.org> >> CommitDate: 2021-04-01 08:03:30 +0000 >> >> tcp: For hostcache performance, use atomics instead of counters > > Is that an April 1st joke, or for real, since it appears to have hit > the tree? > >> As accessing the tcp hostcache happens frequently on some >> classes of servers, it was recommended > > Recommended by whom? See https://reviews.freebsd.org/D29510#661680
Best regards Michael > >> to use atomic_add/subtract >> rather than (per-CPU distributed) counters, which have to be >> summed up at high cost to cache efficiency. > > Numbers? > >> >> PR: 254333 >> MFC after: 2 weeks >> Sponsored by: NetApp, Inc. >> Reviewed By: #transport, tuexen, jtl >> Differential Revision: https://reviews.freebsd.org/D29522 >> --- >> sys/netinet/tcp_hostcache.c | 24 +++++++++++------------- >> sys/netinet/tcp_hostcache.h | 2 +- >> 2 files changed, 12 insertions(+), 14 deletions(-) >> >> diff --git a/sys/netinet/tcp_hostcache.c b/sys/netinet/tcp_hostcache.c >> index 67da97405c3f..87023cc1a760 100644 >> --- a/sys/netinet/tcp_hostcache.c >> +++ b/sys/netinet/tcp_hostcache.c >> @@ -147,8 +147,8 @@ SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, >> bucketlimit, CTLFLAG_VNET | CTLFLAG_RDTUN, >> &VNET_NAME(tcp_hostcache.bucket_limit), 0, "Per-bucket hash limit for >> hostcache"); >> -SYSCTL_COUNTER_U64(_net_inet_tcp_hostcache, OID_AUTO, count, >> CTLFLAG_VNET | CTLFLAG_RD, >> - &VNET_NAME(tcp_hostcache.cache_count), >> +SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_VNET | >> CTLFLAG_RD, >> + &VNET_NAME(tcp_hostcache.cache_count), 0, >> "Current number of entries in hostcache"); >> >> SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_VNET | >> CTLFLAG_RW, @@ -199,8 +199,7 @@ tcp_hc_init(void) >> /* >> * Initialize hostcache structures. >> */ >> - V_tcp_hostcache.cache_count = counter_u64_alloc(M_WAITOK); >> - counter_u64_zero(V_tcp_hostcache.cache_count); >> + atomic_store_int(&V_tcp_hostcache.cache_count, 0); >> V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; >> V_tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT; >> V_tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE; >> @@ -268,9 +267,6 @@ tcp_hc_destroy(void) >> /* Purge all hc entries. */ >> tcp_hc_purge_internal(1); >> >> - /* Release the counter */ >> - counter_u64_free(V_tcp_hostcache.cache_count); >> - >> /* Free the uma zone and the allocated hash table. */ >> uma_zdestroy(V_tcp_hostcache.zone); >> >> @@ -378,7 +374,7 @@ tcp_hc_insert(struct in_conninfo *inc) >> * If the bucket limit is reached, reuse the least-used >> element. */ >> if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit || >> - counter_u64_fetch(V_tcp_hostcache.cache_count) >= >> V_tcp_hostcache.cache_limit) { >> + atomic_load_int(&V_tcp_hostcache.cache_count) >= >> V_tcp_hostcache.cache_limit) { hc_entry = >> TAILQ_LAST(&hc_head->hch_bucket, hc_qhead); /* >> * At first we were dropping the last element, just >> to @@ -395,7 +391,7 @@ tcp_hc_insert(struct in_conninfo *inc) >> } >> TAILQ_REMOVE(&hc_head->hch_bucket, hc_entry, rmx_q); >> V_tcp_hostcache.hashbase[hash].hch_length--; >> - counter_u64_add(V_tcp_hostcache.cache_count, -1); >> + atomic_subtract_int(&V_tcp_hostcache.cache_count, 1); >> TCPSTAT_INC(tcps_hc_bucketoverflow); >> #if 0 >> uma_zfree(V_tcp_hostcache.zone, hc_entry); >> @@ -428,7 +424,7 @@ tcp_hc_insert(struct in_conninfo *inc) >> */ >> TAILQ_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q); >> V_tcp_hostcache.hashbase[hash].hch_length++; >> - counter_u64_add(V_tcp_hostcache.cache_count, 1); >> + atomic_add_int(&V_tcp_hostcache.cache_count, 1); >> TCPSTAT_INC(tcps_hc_added); >> >> return hc_entry; >> @@ -644,7 +640,8 @@ sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS) >> >> /* Optimize Buffer length query by sbin/sysctl */ >> if (req->oldptr == NULL) { >> - len = >> (counter_u64_fetch(V_tcp_hostcache.cache_count) + 1) * linesize; >> + len = (atomic_load_int(&V_tcp_hostcache.cache_count) >> + 1) * >> + linesize; >> return (SYSCTL_OUT(req, NULL, len)); >> } >> >> @@ -654,7 +651,8 @@ sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS) >> } >> >> /* Use a buffer sized for one full bucket */ >> - sbuf_new_for_sysctl(&sb, NULL, V_tcp_hostcache.bucket_limit >> * linesize, req); >> + sbuf_new_for_sysctl(&sb, NULL, V_tcp_hostcache.bucket_limit * >> + linesize, req); >> >> sbuf_printf(&sb, >> "\nIP address MTU SSTRESH RTT RTTVAR " >> @@ -716,7 +714,7 @@ tcp_hc_purge_internal(int all) >> hc_entry, rmx_q); >> uma_zfree(V_tcp_hostcache.zone, >> hc_entry); V_tcp_hostcache.hashbase[i].hch_length--; >> - >> counter_u64_add(V_tcp_hostcache.cache_count, -1); >> + >> atomic_subtract_int(&V_tcp_hostcache.cache_count, 1); } else >> hc_entry->rmx_expire -= >> V_tcp_hostcache.prune; } >> diff --git a/sys/netinet/tcp_hostcache.h b/sys/netinet/tcp_hostcache.h >> index b5237392acc2..2f7035c0c6af 100644 >> --- a/sys/netinet/tcp_hostcache.h >> +++ b/sys/netinet/tcp_hostcache.h >> @@ -74,7 +74,7 @@ struct tcp_hostcache { >> u_int hashsize; >> u_int hashmask; >> u_int bucket_limit; >> - counter_u64_t cache_count; >> + u_int cache_count; >> u_int cache_limit; >> int expire; >> int prune; > _______________________________________________ dev-commits-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/dev-commits-src-all To unsubscribe, send any mail to "dev-commits-src-all-unsubscr...@freebsd.org"
