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Commit fdfb70d2 authored by stephen hemminger's avatar stephen hemminger Committed by David S. Miller
Browse files

netvsc: fix calculation of available send sections 



My change (introduced in 4.11) to use find_first_clear_bit
incorrectly assumed that the size argument was words, not bits.
The effect was only a small limited number of the available send
sections were being actually used. This can cause performance loss
with some workloads.

Since map_words is now used only during initialization, it can
be on stack instead of in per-device data.

Fixes: b58a1858 ("netvsc: simplify get next send section")
Signed-off-by: default avatarStephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a23f6ce6

drivers/net/hyperv/hyperv_net.h

+0 −1
Original line number Diff line number Diff line
@@ -751,7 +751,6 @@ struct netvsc_device { 
	u32 send_section_cnt;

	u32 send_section_size;

	unsigned long *send_section_map;

	int map_words;



	/* Used for NetVSP initialization protocol */

	struct completion channel_init_wait;

drivers/net/hyperv/netvsc.c

+4 −5
Original line number Diff line number Diff line
@@ -236,6 +236,7 @@ static int netvsc_init_buf(struct hv_device *device) 
	struct netvsc_device *net_device;

	struct nvsp_message *init_packet;

	struct net_device *ndev;

	size_t map_words;

	int node;



	net_device = get_outbound_net_device(device);
@@ -401,11 +402,9 @@ static int netvsc_init_buf(struct hv_device *device) 
		   net_device->send_section_size, net_device->send_section_cnt);



	/* Setup state for managing the send buffer. */

	net_device->map_words = DIV_ROUND_UP(net_device->send_section_cnt,

					     BITS_PER_LONG);

	map_words = DIV_ROUND_UP(net_device->send_section_cnt, BITS_PER_LONG);



	net_device->send_section_map = kcalloc(net_device->map_words,

					       sizeof(ulong), GFP_KERNEL);

	net_device->send_section_map = kcalloc(map_words, sizeof(ulong), GFP_KERNEL);

	if (net_device->send_section_map == NULL) {

		ret = -ENOMEM;

		goto cleanup;
@@ -683,7 +682,7 @@ static u32 netvsc_get_next_send_section(struct netvsc_device *net_device) 
	unsigned long *map_addr = net_device->send_section_map;

	unsigned int i;



	for_each_clear_bit(i, map_addr, net_device->map_words) {

	for_each_clear_bit(i, map_addr, net_device->send_section_cnt) {

		if (sync_test_and_set_bit(i, map_addr) == 0)

			return i;

	}