Author: grehan
Date: Fri Apr 26 05:13:48 2013
New Revision: 249917
URL: http://svnweb.freebsd.org/changeset/base/249917
Log:
Use a thread for the processing of virtio tx descriptors rather
than blocking the vCPU thread. This improves bulk data performance
by ~30-40% and doesn't harm req/resp time for stock netperf runs.
Future work will use a thread pool rather than a thread per tx queue.
Submitted by: Dinakar Medavaram
Reviewed by: neel, grehan
Obtained from: NetApp
Modified:
head/usr.sbin/bhyve/pci_virtio_net.c
Modified: head/usr.sbin/bhyve/pci_virtio_net.c
==============================================================================
--- head/usr.sbin/bhyve/pci_virtio_net.c Fri Apr 26 02:24:50 2013
(r249916)
+++ head/usr.sbin/bhyve/pci_virtio_net.c Fri Apr 26 05:13:48 2013
(r249917)
@@ -46,13 +46,14 @@ __FBSDID("$FreeBSD$");
#include <assert.h>
#include <md5.h>
#include <pthread.h>
+#include <pthread_np.h>
#include "bhyverun.h"
#include "pci_emul.h"
#include "mevent.h"
#include "virtio.h"
-#define VTNET_RINGSZ 256
+#define VTNET_RINGSZ 1024
#define VTNET_MAXSEGS 32
@@ -140,6 +141,8 @@ struct pci_vtnet_softc {
int vsc_tapfd;
int vsc_rx_ready;
int vsc_rxpend;
+ int tx_in_progress;
+ int resetting;
uint32_t vsc_features;
uint8_t vsc_macaddr[6];
@@ -147,6 +150,9 @@ struct pci_vtnet_softc {
uint64_t vsc_pfn[VTNET_MAXQ];
struct vring_hqueue vsc_hq[VTNET_MAXQ];
uint16_t vsc_msix_table_idx[VTNET_MAXQ];
+ pthread_t tx_tid;
+ pthread_mutex_t tx_mtx;
+ pthread_cond_t tx_cond;
};
#define vtnet_ctx(sc) ((sc)->vsc_pi->pi_vmctx)
@@ -174,7 +180,7 @@ hq_num_avail(struct vring_hqueue *hq)
uint16_t ndesc;
/*
- * We're just computing (a-b) in GF(216).
+ * We're just computing (a-b) mod 2^16
*
* The only glitch here is that in standard C,
* uint16_t promotes to (signed) int when int has
@@ -221,9 +227,23 @@ pci_vtnet_update_status(struct pci_vtnet
if (value == 0) {
DPRINTF(("vtnet: device reset requested !\n"));
+
+ /* Wait for TX thread to complete pending desc processing */
+ sc->resetting = 1;
+ pthread_mutex_lock(&sc->tx_mtx);
+
+ while (sc->tx_in_progress) {
+ pthread_mutex_unlock(&sc->tx_mtx);
+ usleep(10000);
+ pthread_mutex_lock(&sc->tx_mtx);
+ }
+
+ pthread_mutex_unlock(&sc->tx_mtx);
+
pci_vtnet_ring_reset(sc, VTNET_RXQ);
pci_vtnet_ring_reset(sc, VTNET_TXQ);
sc->vsc_rx_ready = 0;
+ sc->resetting = 0;
}
sc->vsc_status = value;
@@ -463,25 +483,12 @@ pci_vtnet_proctx(struct pci_vtnet_softc
hq->hq_cur_aidx = aidx + 1;
*hq->hq_used_idx = uidx + 1;
- /*
- * Generate an interrupt if able
- */
- if ((*hq->hq_avail_flags & VRING_AVAIL_F_NO_INTERRUPT) == 0) {
- if (use_msix) {
- pci_generate_msix(sc->vsc_pi,
- sc->vsc_msix_table_idx[VTNET_TXQ]);
- } else {
- sc->vsc_isr |= 1;
- pci_generate_msi(sc->vsc_pi, 0);
- }
- }
}
static void
pci_vtnet_ping_txq(struct pci_vtnet_softc *sc)
{
struct vring_hqueue *hq = &sc->vsc_hq[VTNET_TXQ];
- int i;
int ndescs;
/*
@@ -492,14 +499,82 @@ pci_vtnet_ping_txq(struct pci_vtnet_soft
if (ndescs == 0)
return;
- /*
- * Run through all the entries, placing them into iovecs and
- * sending when an end-of-packet is found
- */
- for (i = 0; i < ndescs; i++)
- pci_vtnet_proctx(sc, hq);
+ /* Signal the tx thread for processing */
+ pthread_mutex_lock(&sc->tx_mtx);
+ if (sc->tx_in_progress == 0)
+ pthread_cond_signal(&sc->tx_cond);
+ pthread_mutex_unlock(&sc->tx_mtx);
}
+/*
+ * Thread which will handle processing of TX desc
+ */
+static void *
+pci_vtnet_tx_thread(void *param)
+{
+ struct pci_vtnet_softc *sc = (struct pci_vtnet_softc *) param;
+ struct vring_hqueue *hq;
+ int i, ndescs, needintr,error;
+
+ needintr = 0;
+ hq = &sc->vsc_hq[VTNET_TXQ];
+
+ /*
+ * Let us wait till the tx queue pointers get initialised &
+ * first tx signaled
+ */
+ pthread_mutex_lock(&sc->tx_mtx);
+ error = pthread_cond_wait(&sc->tx_cond, &sc->tx_mtx);
+ assert(error == 0);
+
+ for (;;) {
+ pthread_mutex_lock(&sc->tx_mtx);
+ for (;;) {
+ if (sc->resetting) {
+ ndescs = 0;
+ needintr = 0;
+ } else
+ ndescs = hq_num_avail(hq);
+
+ if (ndescs != 0)
+ break;
+
+ if (needintr) {
+ /*
+ * Generate an interrupt if able
+ */
+ if ((*hq->hq_avail_flags &
+ VRING_AVAIL_F_NO_INTERRUPT) == 0) {
+ if (use_msix) {
+ pci_generate_msix(sc->vsc_pi,
+
sc->vsc_msix_table_idx[VTNET_TXQ]);
+ } else {
+ sc->vsc_isr |= 1;
+ pci_generate_msi(sc->vsc_pi, 0);
+ }
+ }
+ }
+ needintr = 0;
+ sc->tx_in_progress = 0;
+ error = pthread_cond_wait(&sc->tx_cond, &sc->tx_mtx);
+ assert(error == 0);
+ }
+ sc->tx_in_progress = 1;
+ pthread_mutex_unlock(&sc->tx_mtx);
+
+ while (ndescs > 0) {
+ /*
+ * Run through all the entries, placing them into
+ * iovecs and sending when an end-of-packet is found
+ */
+ for (i = 0; i < ndescs; i++)
+ pci_vtnet_proctx(sc, hq);
+ needintr = 1;
+ ndescs = hq_num_avail(hq);
+ }
+ }
+}
+
static void
pci_vtnet_ping_ctlq(struct pci_vtnet_softc *sc)
{
@@ -546,6 +621,7 @@ pci_vtnet_init(struct vmctx *ctx, struct
MD5_CTX mdctx;
unsigned char digest[16];
char nstr[80];
+ char tname[MAXCOMLEN + 1];
struct pci_vtnet_softc *sc;
const char *env_msi;
@@ -650,7 +726,21 @@ pci_vtnet_init(struct vmctx *ctx, struct
}
pci_emul_alloc_bar(pi, 0, PCIBAR_IO, VTNET_REGSZ);
+
+ /*
+ * Initialize tx semaphore & spawn TX processing thread
+ * As of now, only one thread for TX desc processing is
+ * spawned.
+ */
+ sc->tx_in_progress = 0;
+ sc->resetting = 0;
+ pthread_mutex_init(&sc->tx_mtx, NULL);
+ pthread_cond_init(&sc->tx_cond, NULL);
+ pthread_create(&sc->tx_tid, NULL, pci_vtnet_tx_thread, (void *)sc);
+ snprintf(tname, sizeof(tname), "%s vtnet%d tx", vmname, pi->pi_slot);
+ pthread_set_name_np(sc->tx_tid, tname);
+
return (0);
}
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