From: Stephen Hemminger <stephen@networkplumber•org>
To: davem@davemloft•net
Cc: netdev@vger•kernel.org, Stephen Hemminger <sthemmin@microsoft•com>
Subject: [PATCH net] netvsc: fix calculation of available send sections
Date: Mon, 24 Apr 2017 18:33:38 -0700 [thread overview]
Message-ID: <20170425013338.2653-1-sthemmin@microsoft.com> (raw)
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: b58a185801da ("netvsc: simplify get next send section")
Signed-off-by: Stephen Hemminger <sthemmin@microsoft•com>
---
drivers/net/hyperv/hyperv_net.h | 1 -
drivers/net/hyperv/netvsc.c | 9 ++++-----
2 files changed, 4 insertions(+), 6 deletions(-)
diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index f9f3dba7a588..db23cb36ae5c 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -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;
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 8dd0b8770328..15ef713d96c0 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -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;
}
--
2.11.0
next reply other threads:[~2017-04-25 1:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-25 1:33 Stephen Hemminger [this message]
2017-04-25 3:20 ` [PATCH net] netvsc: fix calculation of available send sections Greg Rose
2017-04-25 15:57 ` David Miller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170425013338.2653-1-sthemmin@microsoft.com \
--to=stephen@networkplumber$(echo .)org \
--cc=davem@davemloft$(echo .)net \
--cc=netdev@vger$(echo .)kernel.org \
--cc=sthemmin@microsoft$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox