svn commit: r295748 - head/sys/dev/hyperv/netvsc
Sepherosa Ziehau
sephe at FreeBSD.org
Thu Feb 18 07:44:15 UTC 2016
Author: sephe
Date: Thu Feb 18 07:44:14 2016
New Revision: 295748
URL: https://svnweb.freebsd.org/changeset/base/295748
Log:
hyperv/hn: Use buf_ring for txdesc list
So one spinlock is avoided, which would be potentially dangerous for
virtual machine, if the spinlock holder was scheduled out by the host,
as noted by royger.
Old spinlock based txdesc list is still kept around, so we could have
a safe fallback.
No performance regression nor improvement is observed.
Reviewed by: adrian
Approved by: adrian (mentor)
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D5290
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 07:37:59 2016 (r295747)
+++ head/sys/dev/hyperv/netvsc/hv_net_vsc.h Thu Feb 18 07:44:14 2016 (r295748)
@@ -58,6 +58,8 @@
#include <dev/hyperv/include/hyperv.h>
+#define HN_USE_TXDESC_BUFRING
+
MALLOC_DECLARE(M_NETVSC);
#define NVSP_INVALID_PROTOCOL_VERSION (0xFFFFFFFF)
@@ -990,8 +992,12 @@ typedef struct {
hv_bool_uint8_t link_state;
} netvsc_device_info;
+#ifndef HN_USE_TXDESC_BUFRING
struct hn_txdesc;
SLIST_HEAD(hn_txdesc_list, hn_txdesc);
+#else
+struct buf_ring;
+#endif
struct hn_rx_ring {
struct lro_ctrl hn_lro;
@@ -1012,8 +1018,12 @@ struct hn_rx_ring {
#define HN_TRUST_HCSUM_UDP 0x0004
struct hn_tx_ring {
+#ifndef HN_USE_TXDESC_BUFRING
struct mtx hn_txlist_spin;
struct hn_txdesc_list hn_txlist;
+#else
+ struct buf_ring *hn_txdesc_br;
+#endif
int hn_txdesc_cnt;
int hn_txdesc_avail;
int hn_txeof;
Modified: head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
==============================================================================
--- head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c Thu Feb 18 07:37:59 2016 (r295747)
+++ head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c Thu Feb 18 07:44:14 2016 (r295748)
@@ -70,6 +70,7 @@ __FBSDID("$FreeBSD$");
#include <sys/lock.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
+#include <sys/buf_ring.h>
#include <net/if.h>
#include <net/if_arp.h>
@@ -151,7 +152,9 @@ __FBSDID("$FreeBSD$");
#define HN_DIRECT_TX_SIZE_DEF 128
struct hn_txdesc {
+#ifndef HN_USE_TXDESC_BUFRING
SLIST_ENTRY(hn_txdesc) link;
+#endif
struct mbuf *m;
struct hn_tx_ring *txr;
int refs;
@@ -258,6 +261,14 @@ SYSCTL_INT(_hw_hn, OID_AUTO, share_tx_ta
static struct taskqueue *hn_tx_taskq;
+#ifndef HN_USE_TXDESC_BUFRING
+static int hn_use_txdesc_bufring = 0;
+#else
+static int hn_use_txdesc_bufring = 1;
+#endif
+SYSCTL_INT(_hw_hn, OID_AUTO, use_txdesc_bufring, CTLFLAG_RD,
+ &hn_use_txdesc_bufring, 0, "Use buf_ring for TX descriptors");
+
/*
* Forward declarations
*/
@@ -570,6 +581,7 @@ hn_txdesc_put(struct hn_tx_ring *txr, st
txd->flags |= HN_TXD_FLAG_ONLIST;
+#ifndef HN_USE_TXDESC_BUFRING
mtx_lock_spin(&txr->hn_txlist_spin);
KASSERT(txr->hn_txdesc_avail >= 0 &&
txr->hn_txdesc_avail < txr->hn_txdesc_cnt,
@@ -577,6 +589,10 @@ hn_txdesc_put(struct hn_tx_ring *txr, st
txr->hn_txdesc_avail++;
SLIST_INSERT_HEAD(&txr->hn_txlist, txd, link);
mtx_unlock_spin(&txr->hn_txlist_spin);
+#else
+ atomic_add_int(&txr->hn_txdesc_avail, 1);
+ buf_ring_enqueue(txr->hn_txdesc_br, txd);
+#endif
return 1;
}
@@ -586,6 +602,7 @@ hn_txdesc_get(struct hn_tx_ring *txr)
{
struct hn_txdesc *txd;
+#ifndef HN_USE_TXDESC_BUFRING
mtx_lock_spin(&txr->hn_txlist_spin);
txd = SLIST_FIRST(&txr->hn_txlist);
if (txd != NULL) {
@@ -595,8 +612,14 @@ hn_txdesc_get(struct hn_tx_ring *txr)
SLIST_REMOVE_HEAD(&txr->hn_txlist, link);
}
mtx_unlock_spin(&txr->hn_txlist_spin);
+#else
+ txd = buf_ring_dequeue_sc(txr->hn_txdesc_br);
+#endif
if (txd != NULL) {
+#ifdef HN_USE_TXDESC_BUFRING
+ atomic_subtract_int(&txr->hn_txdesc_avail, 1);
+#endif
KASSERT(txd->m == NULL && txd->refs == 0 &&
(txd->flags & HN_TXD_FLAG_ONLIST), ("invalid txd"));
txd->flags &= ~HN_TXD_FLAG_ONLIST;
@@ -2048,13 +2071,20 @@ hn_create_tx_ring(struct hn_softc *sc, i
txr->hn_sc = sc;
+#ifndef HN_USE_TXDESC_BUFRING
mtx_init(&txr->hn_txlist_spin, "hn txlist", NULL, MTX_SPIN);
+#endif
mtx_init(&txr->hn_tx_lock, "hn tx", NULL, MTX_DEF);
txr->hn_txdesc_cnt = HN_TX_DESC_CNT;
txr->hn_txdesc = malloc(sizeof(struct hn_txdesc) * txr->hn_txdesc_cnt,
M_NETVSC, M_WAITOK | M_ZERO);
+#ifndef HN_USE_TXDESC_BUFRING
SLIST_INIT(&txr->hn_txlist);
+#else
+ txr->hn_txdesc_br = buf_ring_alloc(txr->hn_txdesc_cnt, M_NETVSC,
+ M_WAITOK, &txr->hn_tx_lock);
+#endif
txr->hn_tx_taskq = sc->hn_tx_taskq;
TASK_INIT(&txr->hn_start_task, 0, hn_start_taskfunc, txr);
@@ -2158,7 +2188,11 @@ hn_create_tx_ring(struct hn_softc *sc, i
/* All set, put it to list */
txd->flags |= HN_TXD_FLAG_ONLIST;
+#ifndef HN_USE_TXDESC_BUFRING
SLIST_INSERT_HEAD(&txr->hn_txlist, txd, link);
+#else
+ buf_ring_enqueue(txr->hn_txdesc_br, txd);
+#endif
}
txr->hn_txdesc_avail = txr->hn_txdesc_cnt;
@@ -2191,6 +2225,20 @@ hn_create_tx_ring(struct hn_softc *sc, i
}
static void
+hn_txdesc_dmamap_destroy(struct hn_txdesc *txd)
+{
+ struct hn_tx_ring *txr = txd->txr;
+
+ KASSERT(txd->m == NULL, ("still has mbuf installed"));
+ KASSERT((txd->flags & HN_TXD_FLAG_DMAMAP) == 0, ("still dma mapped"));
+
+ bus_dmamap_unload(txr->hn_tx_rndis_dtag, txd->rndis_msg_dmap);
+ bus_dmamem_free(txr->hn_tx_rndis_dtag, txd->rndis_msg,
+ txd->rndis_msg_dmap);
+ bus_dmamap_destroy(txr->hn_tx_data_dtag, txd->data_dmap);
+}
+
+static void
hn_destroy_tx_ring(struct hn_tx_ring *txr)
{
struct hn_txdesc *txd;
@@ -2198,19 +2246,15 @@ hn_destroy_tx_ring(struct hn_tx_ring *tx
if (txr->hn_txdesc == NULL)
return;
+#ifndef HN_USE_TXDESC_BUFRING
while ((txd = SLIST_FIRST(&txr->hn_txlist)) != NULL) {
- KASSERT(txd->m == NULL, ("still has mbuf installed"));
- KASSERT((txd->flags & HN_TXD_FLAG_DMAMAP) == 0,
- ("still dma mapped"));
SLIST_REMOVE_HEAD(&txr->hn_txlist, link);
-
- bus_dmamap_unload(txr->hn_tx_rndis_dtag,
- txd->rndis_msg_dmap);
- bus_dmamem_free(txr->hn_tx_rndis_dtag,
- txd->rndis_msg, txd->rndis_msg_dmap);
-
- bus_dmamap_destroy(txr->hn_tx_data_dtag, txd->data_dmap);
+ hn_txdesc_dmamap_destroy(txd);
}
+#else
+ while ((txd = buf_ring_dequeue_sc(txr->hn_txdesc_br)) != NULL)
+ hn_txdesc_dmamap_destroy(txd);
+#endif
if (txr->hn_tx_data_dtag != NULL)
bus_dma_tag_destroy(txr->hn_tx_data_dtag);
@@ -2219,7 +2263,9 @@ hn_destroy_tx_ring(struct hn_tx_ring *tx
free(txr->hn_txdesc, M_NETVSC);
txr->hn_txdesc = NULL;
+#ifndef HN_USE_TXDESC_BUFRING
mtx_destroy(&txr->hn_txlist_spin);
+#endif
mtx_destroy(&txr->hn_tx_lock);
}
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