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
As accessing the tcp hostcache happens frequently on some
classes of servers, it was recommended to use atomic_add/subtract
rather than (per-CPU distributed) counters, which have to be
summed up at high cost to cache efficiency.
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;
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