Date: Thu, 18 Feb 2016 07:44:14 +0000 (UTC) From: Sepherosa Ziehau <sephe@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r295748 - head/sys/dev/hyperv/netvsc Message-ID: <201602180744.u1I7iEhW064867@repo.freebsd.org>
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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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