svn commit: r295740 - head/sys/dev/hyperv/netvsc
Sepherosa Ziehau
sephe at FreeBSD.org
Thu Feb 18 04:59:39 UTC 2016
Author: sephe
Date: Thu Feb 18 04:59:37 2016
New Revision: 295740
URL: https://svnweb.freebsd.org/changeset/base/295740
Log:
hyperv/hn: Set the TCP ACK/data segment aggregation limit
Set TCP ACK append limit to 1, i.e. aggregate 2 ACKs at most. Aggregating
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 it greatly stabilizes the TCP
sending performance in other cases.
Set TCP data segments aggregation length limit to 37500. 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.
Reviewed by: adrian, gallatin (previous version), hselasky (previous version)
Approved by: adrian (mentor)
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D5185
Modified:
head/sys/dev/hyperv/netvsc/hv_net_vsc.h
head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
Modified: head/sys/dev/hyperv/netvsc/hv_net_vsc.h
==============================================================================
--- head/sys/dev/hyperv/netvsc/hv_net_vsc.h Thu Feb 18 04:58:34 2016 (r295739)
+++ head/sys/dev/hyperv/netvsc/hv_net_vsc.h Thu Feb 18 04:59:37 2016 (r295740)
@@ -1030,7 +1030,6 @@ typedef struct hn_softc {
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_ */
Modified: head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
==============================================================================
--- head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c Thu Feb 18 04:58:34 2016 (r295739)
+++ head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c Thu Feb 18 04:59:37 2016 (r295740)
@@ -176,14 +176,11 @@ struct hn_txdesc {
#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
+#define HN_LRO_LENLIM_DEF (25 * ETHERMTU)
/* 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_LENLIM_MIN(ifp) (2 * (ifp)->if_mtu)
+
+#define HN_LRO_ACKCNT_DEF 1
/*
* Be aware that this sleepable mutex will exhibit WITNESS errors when
@@ -253,9 +250,8 @@ static void hn_start(struct ifnet *ifp);
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_lro_lenlim_sysctl(SYSCTL_HANDLER_ARGS);
+static int hn_lro_ackcnt_sysctl(SYSCTL_HANDLER_ARGS);
static int hn_trust_hcsum_sysctl(SYSCTL_HANDLER_ARGS);
static int hn_tx_chimney_size_sysctl(SYSCTL_HANDLER_ARGS);
static int hn_check_iplen(const struct mbuf *, int);
@@ -265,15 +261,6 @@ static void hn_start_taskfunc(void *xsc,
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 +345,6 @@ netvsc_attach(device_t dev)
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 +428,8 @@ netvsc_attach(device_t dev)
/* 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_length_lim = HN_LRO_LENLIM_DEF;
+ sc->hn_lro.lro_ackcnt_lim = HN_LRO_ACKCNT_DEF;
#endif /* INET || INET6 */
#if __FreeBSD_version >= 1100045
@@ -480,11 +465,12 @@ netvsc_attach(device_t dev)
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, "lro_length_lim",
+ CTLTYPE_UINT | CTLFLAG_RW, sc, 0, hn_lro_lenlim_sysctl, "IU",
+ "Max # of data bytes to be aggregated by LRO");
+ SYSCTL_ADD_PROC(ctx, child, OID_AUTO, "lro_ackcnt_lim",
+ CTLTYPE_INT | CTLFLAG_RW, sc, 0, hn_lro_ackcnt_sysctl, "I",
+ "Max # of ACKs to be aggregated by LRO");
SYSCTL_ADD_PROC(ctx, child, OID_AUTO, "trust_hosttcp",
CTLTYPE_INT | CTLFLAG_RW, sc, HN_TRUST_HCSUM_TCP,
hn_trust_hcsum_sysctl, "I",
@@ -1410,12 +1396,13 @@ hn_ioctl(struct ifnet *ifp, u_long cmd,
/* 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).
+ * Make sure that LRO aggregation length limit is still
+ * valid, after the MTU change.
*/
- if (!HN_LRO_HIWAT_ISVALID(sc, sc->hn_lro_hiwat))
- hn_set_lro_hiwat(sc, HN_LRO_HIWAT_MTULIM(ifp));
+ if (sc->hn_lro.lro_length_lim < HN_LRO_LENLIM_MIN(ifp))
+ sc->hn_lro.lro_length_lim = HN_LRO_LENLIM_MIN(ifp);
do {
NV_LOCK(sc);
@@ -1722,26 +1709,51 @@ hn_watchdog(struct ifnet *ifp)
}
#endif
-#ifdef HN_LRO_HIWAT
static int
-hn_lro_hiwat_sysctl(SYSCTL_HANDLER_ARGS)
+hn_lro_lenlim_sysctl(SYSCTL_HANDLER_ARGS)
{
struct hn_softc *sc = arg1;
- int hiwat, error;
+ unsigned int lenlim;
+ int error;
- hiwat = sc->hn_lro_hiwat;
- error = sysctl_handle_int(oidp, &hiwat, 0, req);
+ lenlim = sc->hn_lro.lro_length_lim;
+ error = sysctl_handle_int(oidp, &lenlim, 0, req);
if (error || req->newptr == NULL)
return error;
- if (!HN_LRO_HIWAT_ISVALID(sc, hiwat))
+ if (lenlim < HN_LRO_LENLIM_MIN(sc->hn_ifp) ||
+ lenlim > TCP_LRO_LENGTH_MAX)
return EINVAL;
- if (sc->hn_lro_hiwat != hiwat)
- hn_set_lro_hiwat(sc, hiwat);
+ sc->hn_lro.lro_length_lim = lenlim;
+ return 0;
+}
+
+static int
+hn_lro_ackcnt_sysctl(SYSCTL_HANDLER_ARGS)
+{
+ struct hn_softc *sc = arg1;
+ int ackcnt, error;
+
+ /*
+ * lro_ackcnt_lim is append count limit,
+ * +1 to turn it into aggregation limit.
+ */
+ ackcnt = sc->hn_lro.lro_ackcnt_lim + 1;
+ error = sysctl_handle_int(oidp, &ackcnt, 0, req);
+ if (error || req->newptr == NULL)
+ return error;
+
+ if (ackcnt < 2 || ackcnt > (TCP_LRO_ACKCNT_MAX + 1))
+ return EINVAL;
+
+ /*
+ * Convert aggregation limit back to append
+ * count limit.
+ */
+ sc->hn_lro.lro_ackcnt_lim = ackcnt - 1;
return 0;
}
-#endif /* HN_LRO_HIWAT */
static int
hn_trust_hcsum_sysctl(SYSCTL_HANDLER_ARGS)
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