Revision 6e474083f3daf3a3546737f5d7d502ad12eb257c authored by Wei Xu on 01 December 2017, 10:10:36 UTC, committed by David S. Miller on 03 December 2017, 02:31:03 UTC
Matthew found a roughly 40% tcp throughput regression with commit c67df11f(vhost_net: try batch dequing from skb array) as discussed in the following thread: https://www.mail-archive.com/netdev@vger.kernel.org/msg187936.html Eventually we figured out that it was a skb leak in handle_rx() when sending packets to the VM. This usually happens when a guest can not drain out vq as fast as vhost fills in, afterwards it sets off the traffic jam and leaks skb(s) which occurs as no headcount to send on the vq from vhost side. This can be avoided by making sure we have got enough headcount before actually consuming a skb from the batched rx array while transmitting, which is simply done by moving checking the zero headcount a bit ahead. Signed-off-by: Wei Xu <wexu@redhat.com> Reported-by: Matthew Rosato <mjrosato@linux.vnet.ibm.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent fa935ca
leds-syscon.c
/*
* Generic Syscon LEDs Driver
*
* Copyright (c) 2014, Linaro Limited
* Author: Linus Walleij <linus.walleij@linaro.org>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <linux/io.h>
#include <linux/init.h>
#include <linux/of_device.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>
#include <linux/leds.h>
/**
* struct syscon_led - state container for syscon based LEDs
* @cdev: LED class device for this LED
* @map: regmap to access the syscon device backing this LED
* @offset: the offset into the syscon regmap for the LED register
* @mask: the bit in the register corresponding to the LED
* @state: current state of the LED
*/
struct syscon_led {
struct led_classdev cdev;
struct regmap *map;
u32 offset;
u32 mask;
bool state;
};
static void syscon_led_set(struct led_classdev *led_cdev,
enum led_brightness value)
{
struct syscon_led *sled =
container_of(led_cdev, struct syscon_led, cdev);
u32 val;
int ret;
if (value == LED_OFF) {
val = 0;
sled->state = false;
} else {
val = sled->mask;
sled->state = true;
}
ret = regmap_update_bits(sled->map, sled->offset, sled->mask, val);
if (ret < 0)
dev_err(sled->cdev.dev, "error updating LED status\n");
}
static int syscon_led_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node;
struct device *parent;
struct regmap *map;
struct syscon_led *sled;
const char *state;
int ret;
parent = dev->parent;
if (!parent) {
dev_err(dev, "no parent for syscon LED\n");
return -ENODEV;
}
map = syscon_node_to_regmap(parent->of_node);
if (IS_ERR(map)) {
dev_err(dev, "no regmap for syscon LED parent\n");
return PTR_ERR(map);
}
sled = devm_kzalloc(dev, sizeof(*sled), GFP_KERNEL);
if (!sled)
return -ENOMEM;
sled->map = map;
if (of_property_read_u32(np, "offset", &sled->offset))
return -EINVAL;
if (of_property_read_u32(np, "mask", &sled->mask))
return -EINVAL;
sled->cdev.name =
of_get_property(np, "label", NULL) ? : np->name;
sled->cdev.default_trigger =
of_get_property(np, "linux,default-trigger", NULL);
state = of_get_property(np, "default-state", NULL);
if (state) {
if (!strcmp(state, "keep")) {
u32 val;
ret = regmap_read(map, sled->offset, &val);
if (ret < 0)
return ret;
sled->state = !!(val & sled->mask);
} else if (!strcmp(state, "on")) {
sled->state = true;
ret = regmap_update_bits(map, sled->offset,
sled->mask,
sled->mask);
if (ret < 0)
return ret;
} else {
sled->state = false;
ret = regmap_update_bits(map, sled->offset,
sled->mask, 0);
if (ret < 0)
return ret;
}
}
sled->cdev.brightness_set = syscon_led_set;
ret = led_classdev_register(dev, &sled->cdev);
if (ret < 0)
return ret;
platform_set_drvdata(pdev, sled);
dev_info(dev, "registered LED %s\n", sled->cdev.name);
return 0;
}
static const struct of_device_id of_syscon_leds_match[] = {
{ .compatible = "register-bit-led", },
{},
};
static struct platform_driver syscon_led_driver = {
.probe = syscon_led_probe,
.driver = {
.name = "leds-syscon",
.of_match_table = of_syscon_leds_match,
.suppress_bind_attrs = true,
},
};
builtin_platform_driver(syscon_led_driver);
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