p71924506
/
linux_old1
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

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: b58a185801 ("netvsc: simplify get next send section")
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
stephen hemminger 2017-04-24 18:33:38 -07:00 committed by David S. Miller
parent a23f6ce6d9
commit fdfb70d275
2 changed files with 4 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/net/hyperv/hyperv_net.h
View File

@ -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;

9
drivers/net/hyperv/netvsc.c
View File

@ -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;
}