Date: Mon, 02 May 2011 09:33:56 +0200 From: Clemens Ladisch Subject: firewire: optimize iso queueing by setting wake only after the last packet When queueing iso packets, the run time is dominated by the two MMIO accesses that set the DMA context's wake bit. Because most drivers submit packets in batches, we can save much time by removing all but the last wakeup. The internal kernel API is changed to require a call to fw_iso_context_queue_flush() after a batch of queued packets. The user space API does not change, so one call to FW_CDEV_IOC_QUEUE_ISO must specify multiple packets to take advantage of this optimization. In my measurements, this patch reduces the time needed to queue fifty skip packets from userspace to one sixth on a 2.5 GHz CPU, or to one third at 800 MHz. Signed-off-by: Clemens Ladisch Signed-off-by: Stefan Richter --- drivers/firewire/core-card.c | 5 +++++ drivers/firewire/core-cdev.c | 1 + drivers/firewire/core-iso.c | 6 ++++++ drivers/firewire/core.h | 2 ++ drivers/firewire/net.c | 4 +++- drivers/firewire/ohci.c | 19 +++++++++++++++---- drivers/media/dvb/firewire/firedtv-fw.c | 1 + include/linux/firewire.h | 1 + sound/firewire/amdtp.c | 1 + 9 files changed, 35 insertions(+), 5 deletions(-) Index: b/drivers/firewire/core-card.c =================================================================== --- a/drivers/firewire/core-card.c +++ b/drivers/firewire/core-card.c @@ -630,6 +630,10 @@ static int dummy_queue_iso(struct fw_iso return -ENODEV; } +static void dummy_flush_queue_iso(struct fw_iso_context *ctx) +{ +} + static const struct fw_card_driver dummy_driver_template = { .read_phy_reg = dummy_read_phy_reg, .update_phy_reg = dummy_update_phy_reg, @@ -641,6 +645,7 @@ static const struct fw_card_driver dummy .start_iso = dummy_start_iso, .set_iso_channels = dummy_set_iso_channels, .queue_iso = dummy_queue_iso, + .flush_queue_iso = dummy_flush_queue_iso, }; void fw_card_release(struct kref *kref) Index: b/drivers/firewire/core-iso.c =================================================================== --- a/drivers/firewire/core-iso.c +++ b/drivers/firewire/core-iso.c @@ -185,6 +185,12 @@ int fw_iso_context_queue(struct fw_iso_c } EXPORT_SYMBOL(fw_iso_context_queue); +void fw_iso_context_queue_flush(struct fw_iso_context *ctx) +{ + ctx->card->driver->flush_queue_iso(ctx); +} +EXPORT_SYMBOL(fw_iso_context_queue_flush); + int fw_iso_context_stop(struct fw_iso_context *ctx) { return ctx->card->driver->stop_iso(ctx); Index: b/drivers/firewire/core.h =================================================================== --- a/drivers/firewire/core.h +++ b/drivers/firewire/core.h @@ -97,6 +97,8 @@ struct fw_card_driver { struct fw_iso_buffer *buffer, unsigned long payload); + void (*flush_queue_iso)(struct fw_iso_context *ctx); + int (*stop_iso)(struct fw_iso_context *ctx); }; Index: b/drivers/firewire/ohci.c =================================================================== --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -1192,9 +1192,6 @@ static void context_append(struct contex wmb(); /* finish init of new descriptors before branch_address update */ ctx->prev->branch_address = cpu_to_le32(d_bus | z); ctx->prev = find_branch_descriptor(d, z); - - reg_write(ctx->ohci, CONTROL_SET(ctx->regs), CONTEXT_WAKE); - flush_writes(ctx->ohci); } static void context_stop(struct context *ctx) @@ -1348,8 +1345,12 @@ static int at_context_queue_packet(struc context_append(ctx, d, z, 4 - z); - if (!ctx->running) + if (ctx->running) { + reg_write(ohci, CONTROL_SET(ctx->regs), CONTEXT_WAKE); + flush_writes(ohci); + } else { context_run(ctx, 0); + } return 0; } @@ -3121,6 +3122,15 @@ static int ohci_queue_iso(struct fw_iso_ return ret; } +static void ohci_flush_queue_iso(struct fw_iso_context *base) +{ + struct context *ctx = + &container_of(base, struct iso_context, base)->context; + + reg_write(ctx->ohci, CONTROL_SET(ctx->regs), CONTEXT_WAKE); + flush_writes(ctx->ohci); +} + static const struct fw_card_driver ohci_driver = { .enable = ohci_enable, .read_phy_reg = ohci_read_phy_reg, @@ -3137,6 +3147,7 @@ static const struct fw_card_driver ohci_ .free_iso_context = ohci_free_iso_context, .set_iso_channels = ohci_set_iso_channels, .queue_iso = ohci_queue_iso, + .flush_queue_iso = ohci_flush_queue_iso, .start_iso = ohci_start_iso, .stop_iso = ohci_stop_iso, }; Index: b/include/linux/firewire.h =================================================================== --- a/include/linux/firewire.h +++ b/include/linux/firewire.h @@ -440,6 +440,7 @@ int fw_iso_context_queue(struct fw_iso_c struct fw_iso_packet *packet, struct fw_iso_buffer *buffer, unsigned long payload); +void fw_iso_context_queue_flush(struct fw_iso_context *ctx); int fw_iso_context_start(struct fw_iso_context *ctx, int cycle, int sync, int tags); int fw_iso_context_stop(struct fw_iso_context *ctx); Index: b/drivers/firewire/core-cdev.c =================================================================== --- a/drivers/firewire/core-cdev.c +++ b/drivers/firewire/core-cdev.c @@ -1107,6 +1107,7 @@ static int ioctl_queue_iso(struct client payload += u.packet.payload_length; count++; } + fw_iso_context_queue_flush(ctx); a->size -= uptr_to_u64(p) - a->packets; a->packets = uptr_to_u64(p); Index: b/drivers/firewire/net.c =================================================================== --- a/drivers/firewire/net.c +++ b/drivers/firewire/net.c @@ -881,7 +881,9 @@ static void fwnet_receive_broadcast(stru spin_unlock_irqrestore(&dev->lock, flags); - if (retval < 0) + if (retval >= 0) + fw_iso_context_queue_flush(dev->broadcast_rcv_context); + else fw_error("requeue failed\n"); } Index: b/drivers/media/dvb/firewire/firedtv-fw.c =================================================================== --- a/drivers/media/dvb/firewire/firedtv-fw.c +++ b/drivers/media/dvb/firewire/firedtv-fw.c @@ -125,6 +125,7 @@ static void handle_iso(struct fw_iso_con i = (i + 1) & (N_PACKETS - 1); } + fw_iso_context_queue_flush(ctx->context); ctx->current_packet = i; } Index: b/sound/firewire/amdtp.c =================================================================== --- a/sound/firewire/amdtp.c +++ b/sound/firewire/amdtp.c @@ -400,6 +400,7 @@ static void out_packet_callback(struct f for (i = 0; i < packets; ++i) queue_out_packet(s, ++cycle); + fw_iso_context_queue_flush(s->context); } static int queue_initial_skip_packets(struct amdtp_out_stream *s)