sepherosa_gmail.com created this revision.
sepherosa_gmail.com added reviewers: network, adrian, delphij, royger,
decui_microsoft.com, honzhan_microsoft.com, howard0su_gmail.com, gallatin,
hselasky, np.
sepherosa_gmail.com added subscribers: freebsd-net-list,
freebsd-virtualization-list.
Herald added a reviewer: transport.
REVISION SUMMARY
It's append_cnt based. Unless the network driver sets these two limits, its
an NO-OP.
For hn(4):
- Set TCP ACK append limit to 1, i.e. aggregate 2 ACKs at most. Aggregate
anything more than 2 hurts TCP sending performance in hyperv. This
significantly improves the TCP sending performance when the number of
concurrent connetion is low (2~8). And greatly stabilize the TCP sending
performance in other cases.
- Set TCP data segments append limit to 25. Without this limitation, hn(4)
could aggregate ~45 TCP data segments for each connection (even at 64 or more
connections) before dispatching them to socket code; large aggregation slows
down ACK sending and eventually hurts/destabilizes TCP reception performance.
This setting stabilizes and improves TCP reception performance for >4
concurrent connections significantly.
Make them sysctls so they could be adjusted.
REVISION DETAIL
https://reviews.freebsd.org/D5185
AFFECTED FILES
sys/dev/hyperv/netvsc/hv_net_vsc.h
sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
sys/netinet/tcp_lro.c
sys/netinet/tcp_lro.h
EMAIL PREFERENCES
https://reviews.freebsd.org/settings/panel/emailpreferences/
To: sepherosa_gmail.com, network, transport, adrian, delphij, royger,
decui_microsoft.com, honzhan_microsoft.com, howard0su_gmail.com, gallatin,
hselasky, np
Cc: freebsd-virtualization-list, freebsd-net-list
diff --git a/sys/netinet/tcp_lro.h b/sys/netinet/tcp_lro.h
--- a/sys/netinet/tcp_lro.h
+++ b/sys/netinet/tcp_lro.h
@@ -91,6 +91,8 @@
unsigned lro_cnt;
unsigned lro_mbuf_count;
unsigned lro_mbuf_max;
+ unsigned short lro_ack_append_lim;
+ unsigned short lro_data_append_lim;
struct lro_head lro_active;
struct lro_head lro_free;
diff --git a/sys/netinet/tcp_lro.c b/sys/netinet/tcp_lro.c
--- a/sys/netinet/tcp_lro.c
+++ b/sys/netinet/tcp_lro.c
@@ -88,6 +88,8 @@
lc->lro_mbuf_max = lro_mbufs;
lc->lro_cnt = lro_entries;
lc->ifp = ifp;
+ lc->lro_ack_append_lim = 0;
+ lc->lro_data_append_lim = 0;
SLIST_INIT(&lc->lro_free);
SLIST_INIT(&lc->lro_active);
@@ -646,6 +648,16 @@
if (tcp_data_len == 0) {
m_freem(m);
+ /*
+ * Flush this LRO entry, if this ACK should
+ * not be further delayed.
+ */
+ if (lc->lro_ack_append_lim &&
+ le->append_cnt >= lc->lro_ack_append_lim) {
+ SLIST_REMOVE(&lc->lro_active, le, lro_entry,
+ next);
+ tcp_lro_flush(lc, le);
+ }
return (0);
}
@@ -664,9 +676,12 @@
/*
* If a possible next full length packet would cause an
- * overflow, pro-actively flush now.
+ * overflow, pro-actively flush now. And if we are asked
+ * to limit the data aggregate, flush this LRO entry now.
*/
- if (le->p_len > (65535 - lc->ifp->if_mtu)) {
+ if (le->p_len > (65535 - lc->ifp->if_mtu) ||
+ (lc->lro_data_append_lim &&
+ le->append_cnt >= lc->lro_data_append_lim)) {
SLIST_REMOVE(&lc->lro_active, le, lro_entry, next);
tcp_lro_flush(lc, le);
} else
diff --git a/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c b/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
--- a/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
+++ b/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
@@ -176,14 +176,8 @@
#define HN_CSUM_ASSIST_WIN8 (CSUM_TCP)
#define HN_CSUM_ASSIST (CSUM_IP | CSUM_UDP | CSUM_TCP)
-/* XXX move to netinet/tcp_lro.h */
-#define HN_LRO_HIWAT_MAX 65535
-#define HN_LRO_HIWAT_DEF HN_LRO_HIWAT_MAX
-/* YYY 2*MTU is a bit rough, but should be good enough. */
-#define HN_LRO_HIWAT_MTULIM(ifp) (2 * (ifp)->if_mtu)
-#define HN_LRO_HIWAT_ISVALID(sc, hiwat) \
- ((hiwat) >= HN_LRO_HIWAT_MTULIM((sc)->hn_ifp) || \
- (hiwat) <= HN_LRO_HIWAT_MAX)
+#define HN_LRO_ACK_APPEND_LIM 1
+#define HN_LRO_DATA_APPEND_LIM 25
/*
* Be aware that this sleepable mutex will exhibit WITNESS errors when
@@ -253,27 +247,16 @@
static void hn_start_txeof(struct ifnet *ifp);
static int hn_ifmedia_upd(struct ifnet *ifp);
static void hn_ifmedia_sts(struct ifnet *ifp, struct ifmediareq *ifmr);
-#ifdef HN_LRO_HIWAT
-static int hn_lro_hiwat_sysctl(SYSCTL_HANDLER_ARGS);
-#endif
static int hn_trust_hcsum_sysctl(SYSCTL_HANDLER_ARGS);
static int hn_tx_chimney_size_sysctl(SYSCTL_HANDLER_ARGS);
+static int hn_lro_append_lim_sysctl(SYSCTL_HANDLER_ARGS);
static int hn_check_iplen(const struct mbuf *, int);
static int hn_create_tx_ring(struct hn_softc *sc);
static void hn_destroy_tx_ring(struct hn_softc *sc);
static void hn_start_taskfunc(void *xsc, int pending);
static void hn_txeof_taskfunc(void *xsc, int pending);
static int hn_encap(struct hn_softc *, struct hn_txdesc *, struct mbuf **);
-static __inline void
-hn_set_lro_hiwat(struct hn_softc *sc, int hiwat)
-{
- sc->hn_lro_hiwat = hiwat;
-#ifdef HN_LRO_HIWAT
- sc->hn_lro.lro_hiwat = sc->hn_lro_hiwat;
-#endif
-}
-
static int
hn_ifmedia_upd(struct ifnet *ifp __unused)
{
@@ -358,7 +341,6 @@
bzero(sc, sizeof(hn_softc_t));
sc->hn_unit = unit;
sc->hn_dev = dev;
- sc->hn_lro_hiwat = HN_LRO_HIWAT_DEF;
sc->hn_direct_tx_size = hn_direct_tx_size;
if (hn_trust_hosttcp)
sc->hn_trust_hcsum |= HN_TRUST_HCSUM_TCP;
@@ -442,9 +424,8 @@
/* Driver private LRO settings */
sc->hn_lro.ifp = ifp;
#endif
-#ifdef HN_LRO_HIWAT
- sc->hn_lro.lro_hiwat = sc->hn_lro_hiwat;
-#endif
+ sc->hn_lro.lro_ack_append_lim = HN_LRO_ACK_APPEND_LIM;
+ sc->hn_lro.lro_data_append_lim = HN_LRO_DATA_APPEND_LIM;
#endif /* INET || INET6 */
#if __FreeBSD_version >= 1100045
@@ -471,6 +452,13 @@
hn_tx_chimney_size < sc->hn_tx_chimney_max)
sc->hn_tx_chimney_size = hn_tx_chimney_size;
+ /*
+ * Always schedule transmission instead of trying
+ * to do direct transmission. This one gives the
+ * best performance so far.
+ */
+ sc->hn_sched_tx = 1;
+
ctx = device_get_sysctl_ctx(dev);
child = SYSCTL_CHILDREN(device_get_sysctl_tree(dev));
@@ -480,11 +468,6 @@
CTLFLAG_RW, &sc->hn_lro.lro_flushed, 0, "LRO flushed");
SYSCTL_ADD_ULONG(ctx, child, OID_AUTO, "lro_tried",
CTLFLAG_RW, &sc->hn_lro_tried, "# of LRO tries");
-#ifdef HN_LRO_HIWAT
- SYSCTL_ADD_PROC(ctx, child, OID_AUTO, "lro_hiwat",
- CTLTYPE_INT | CTLFLAG_RW, sc, 0, hn_lro_hiwat_sysctl,
- "I", "LRO high watermark");
-#endif
SYSCTL_ADD_PROC(ctx, child, OID_AUTO, "trust_hosttcp",
CTLTYPE_INT | CTLFLAG_RW, sc, HN_TRUST_HCSUM_TCP,
hn_trust_hcsum_sysctl, "I",
@@ -538,6 +521,14 @@
CTLFLAG_RW, &sc->hn_sched_tx, 0,
"Always schedule transmission "
"instead of doing direct transmission");
+ SYSCTL_ADD_PROC(ctx, child, OID_AUTO, "lro_ack_append_lim",
+ CTLTYPE_INT | CTLFLAG_RW, &sc->hn_lro.lro_ack_append_lim,
+ 0, hn_lro_append_lim_sysctl,
+ "I", "LRO ACK appending limitation");
+ SYSCTL_ADD_PROC(ctx, child, OID_AUTO, "lro_data_append_lim",
+ CTLTYPE_INT | CTLFLAG_RW, &sc->hn_lro.lro_data_append_lim,
+ 0, hn_lro_append_lim_sysctl,
+ "I", "LRO data segments appending limitation");
if (unit == 0) {
struct sysctl_ctx_list *dc_ctx;
@@ -1410,13 +1401,6 @@
/* Obtain and record requested MTU */
ifp->if_mtu = ifr->ifr_mtu;
- /*
- * Make sure that LRO high watermark is still valid,
- * after MTU change (the 2*MTU limit).
- */
- if (!HN_LRO_HIWAT_ISVALID(sc, sc->hn_lro_hiwat))
- hn_set_lro_hiwat(sc, HN_LRO_HIWAT_MTULIM(ifp));
-
do {
NV_LOCK(sc);
if (!sc->temp_unusable) {
@@ -1722,27 +1706,6 @@
}
#endif
-#ifdef HN_LRO_HIWAT
-static int
-hn_lro_hiwat_sysctl(SYSCTL_HANDLER_ARGS)
-{
- struct hn_softc *sc = arg1;
- int hiwat, error;
-
- hiwat = sc->hn_lro_hiwat;
- error = sysctl_handle_int(oidp, &hiwat, 0, req);
- if (error || req->newptr == NULL)
- return error;
-
- if (!HN_LRO_HIWAT_ISVALID(sc, hiwat))
- return EINVAL;
-
- if (sc->hn_lro_hiwat != hiwat)
- hn_set_lro_hiwat(sc, hiwat);
- return 0;
-}
-#endif /* HN_LRO_HIWAT */
-
static int
hn_trust_hcsum_sysctl(SYSCTL_HANDLER_ARGS)
{
@@ -1787,6 +1750,24 @@
}
static int
+hn_lro_append_lim_sysctl(SYSCTL_HANDLER_ARGS)
+{
+ unsigned short *lro_lim = arg1;
+ int lim, error;
+
+ lim = *lro_lim;
+ error = sysctl_handle_int(oidp, &lim, 0, req);
+ if (error || req->newptr == NULL)
+ return error;
+
+ if (lim < 0 || lim > 65535)
+ return EINVAL;
+
+ *lro_lim = lim;
+ return 0;
+}
+
+static int
hn_check_iplen(const struct mbuf *m, int hoff)
{
const struct ip *ip;
diff --git a/sys/dev/hyperv/netvsc/hv_net_vsc.h b/sys/dev/hyperv/netvsc/hv_net_vsc.h
--- a/sys/dev/hyperv/netvsc/hv_net_vsc.h
+++ b/sys/dev/hyperv/netvsc/hv_net_vsc.h
@@ -1030,7 +1030,6 @@
struct task hn_txeof_task;
struct lro_ctrl hn_lro;
- int hn_lro_hiwat;
/* Trust csum verification on host side */
int hn_trust_hcsum; /* HN_TRUST_HCSUM_ */
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