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
scompress.c
/*
* Synchronous Compression operations
*
* Copyright 2015 LG Electronics Inc.
* Copyright (c) 2016, Intel Corporation
* Author: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
*
* 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.
*
*/
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/crypto.h>
#include <linux/compiler.h>
#include <linux/vmalloc.h>
#include <crypto/algapi.h>
#include <linux/cryptouser.h>
#include <net/netlink.h>
#include <linux/scatterlist.h>
#include <crypto/scatterwalk.h>
#include <crypto/internal/acompress.h>
#include <crypto/internal/scompress.h>
#include "internal.h"
static const struct crypto_type crypto_scomp_type;
static void * __percpu *scomp_src_scratches;
static void * __percpu *scomp_dst_scratches;
static int scomp_scratch_users;
static DEFINE_MUTEX(scomp_lock);
#ifdef CONFIG_NET
static int crypto_scomp_report(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_comp rscomp;
strncpy(rscomp.type, "scomp", sizeof(rscomp.type));
if (nla_put(skb, CRYPTOCFGA_REPORT_COMPRESS,
sizeof(struct crypto_report_comp), &rscomp))
goto nla_put_failure;
return 0;
nla_put_failure:
return -EMSGSIZE;
}
#else
static int crypto_scomp_report(struct sk_buff *skb, struct crypto_alg *alg)
{
return -ENOSYS;
}
#endif
static void crypto_scomp_show(struct seq_file *m, struct crypto_alg *alg)
__maybe_unused;
static void crypto_scomp_show(struct seq_file *m, struct crypto_alg *alg)
{
seq_puts(m, "type : scomp\n");
}
static void crypto_scomp_free_scratches(void * __percpu *scratches)
{
int i;
if (!scratches)
return;
for_each_possible_cpu(i)
vfree(*per_cpu_ptr(scratches, i));
free_percpu(scratches);
}
static void * __percpu *crypto_scomp_alloc_scratches(void)
{
void * __percpu *scratches;
int i;
scratches = alloc_percpu(void *);
if (!scratches)
return NULL;
for_each_possible_cpu(i) {
void *scratch;
scratch = vmalloc_node(SCOMP_SCRATCH_SIZE, cpu_to_node(i));
if (!scratch)
goto error;
*per_cpu_ptr(scratches, i) = scratch;
}
return scratches;
error:
crypto_scomp_free_scratches(scratches);
return NULL;
}
static void crypto_scomp_free_all_scratches(void)
{
if (!--scomp_scratch_users) {
crypto_scomp_free_scratches(scomp_src_scratches);
crypto_scomp_free_scratches(scomp_dst_scratches);
scomp_src_scratches = NULL;
scomp_dst_scratches = NULL;
}
}
static int crypto_scomp_alloc_all_scratches(void)
{
if (!scomp_scratch_users++) {
scomp_src_scratches = crypto_scomp_alloc_scratches();
if (!scomp_src_scratches)
return -ENOMEM;
scomp_dst_scratches = crypto_scomp_alloc_scratches();
if (!scomp_dst_scratches) {
crypto_scomp_free_scratches(scomp_src_scratches);
scomp_src_scratches = NULL;
return -ENOMEM;
}
}
return 0;
}
static int crypto_scomp_init_tfm(struct crypto_tfm *tfm)
{
int ret;
mutex_lock(&scomp_lock);
ret = crypto_scomp_alloc_all_scratches();
mutex_unlock(&scomp_lock);
return ret;
}
static void crypto_scomp_sg_free(struct scatterlist *sgl)
{
int i, n;
struct page *page;
if (!sgl)
return;
n = sg_nents(sgl);
for_each_sg(sgl, sgl, n, i) {
page = sg_page(sgl);
if (page)
__free_page(page);
}
kfree(sgl);
}
static struct scatterlist *crypto_scomp_sg_alloc(size_t size, gfp_t gfp)
{
struct scatterlist *sgl;
struct page *page;
int i, n;
n = ((size - 1) >> PAGE_SHIFT) + 1;
sgl = kmalloc_array(n, sizeof(struct scatterlist), gfp);
if (!sgl)
return NULL;
sg_init_table(sgl, n);
for (i = 0; i < n; i++) {
page = alloc_page(gfp);
if (!page)
goto err;
sg_set_page(sgl + i, page, PAGE_SIZE, 0);
}
return sgl;
err:
sg_mark_end(sgl + i);
crypto_scomp_sg_free(sgl);
return NULL;
}
static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
{
struct crypto_acomp *tfm = crypto_acomp_reqtfm(req);
void **tfm_ctx = acomp_tfm_ctx(tfm);
struct crypto_scomp *scomp = *tfm_ctx;
void **ctx = acomp_request_ctx(req);
const int cpu = get_cpu();
u8 *scratch_src = *per_cpu_ptr(scomp_src_scratches, cpu);
u8 *scratch_dst = *per_cpu_ptr(scomp_dst_scratches, cpu);
int ret;
if (!req->src || !req->slen || req->slen > SCOMP_SCRATCH_SIZE) {
ret = -EINVAL;
goto out;
}
if (req->dst && !req->dlen) {
ret = -EINVAL;
goto out;
}
if (!req->dlen || req->dlen > SCOMP_SCRATCH_SIZE)
req->dlen = SCOMP_SCRATCH_SIZE;
scatterwalk_map_and_copy(scratch_src, req->src, 0, req->slen, 0);
if (dir)
ret = crypto_scomp_compress(scomp, scratch_src, req->slen,
scratch_dst, &req->dlen, *ctx);
else
ret = crypto_scomp_decompress(scomp, scratch_src, req->slen,
scratch_dst, &req->dlen, *ctx);
if (!ret) {
if (!req->dst) {
req->dst = crypto_scomp_sg_alloc(req->dlen, GFP_ATOMIC);
if (!req->dst)
goto out;
}
scatterwalk_map_and_copy(scratch_dst, req->dst, 0, req->dlen,
1);
}
out:
put_cpu();
return ret;
}
static int scomp_acomp_compress(struct acomp_req *req)
{
return scomp_acomp_comp_decomp(req, 1);
}
static int scomp_acomp_decompress(struct acomp_req *req)
{
return scomp_acomp_comp_decomp(req, 0);
}
static void crypto_exit_scomp_ops_async(struct crypto_tfm *tfm)
{
struct crypto_scomp **ctx = crypto_tfm_ctx(tfm);
crypto_free_scomp(*ctx);
mutex_lock(&scomp_lock);
crypto_scomp_free_all_scratches();
mutex_unlock(&scomp_lock);
}
int crypto_init_scomp_ops_async(struct crypto_tfm *tfm)
{
struct crypto_alg *calg = tfm->__crt_alg;
struct crypto_acomp *crt = __crypto_acomp_tfm(tfm);
struct crypto_scomp **ctx = crypto_tfm_ctx(tfm);
struct crypto_scomp *scomp;
if (!crypto_mod_get(calg))
return -EAGAIN;
scomp = crypto_create_tfm(calg, &crypto_scomp_type);
if (IS_ERR(scomp)) {
crypto_mod_put(calg);
return PTR_ERR(scomp);
}
*ctx = scomp;
tfm->exit = crypto_exit_scomp_ops_async;
crt->compress = scomp_acomp_compress;
crt->decompress = scomp_acomp_decompress;
crt->dst_free = crypto_scomp_sg_free;
crt->reqsize = sizeof(void *);
return 0;
}
struct acomp_req *crypto_acomp_scomp_alloc_ctx(struct acomp_req *req)
{
struct crypto_acomp *acomp = crypto_acomp_reqtfm(req);
struct crypto_tfm *tfm = crypto_acomp_tfm(acomp);
struct crypto_scomp **tfm_ctx = crypto_tfm_ctx(tfm);
struct crypto_scomp *scomp = *tfm_ctx;
void *ctx;
ctx = crypto_scomp_alloc_ctx(scomp);
if (IS_ERR(ctx)) {
kfree(req);
return NULL;
}
*req->__ctx = ctx;
return req;
}
void crypto_acomp_scomp_free_ctx(struct acomp_req *req)
{
struct crypto_acomp *acomp = crypto_acomp_reqtfm(req);
struct crypto_tfm *tfm = crypto_acomp_tfm(acomp);
struct crypto_scomp **tfm_ctx = crypto_tfm_ctx(tfm);
struct crypto_scomp *scomp = *tfm_ctx;
void *ctx = *req->__ctx;
if (ctx)
crypto_scomp_free_ctx(scomp, ctx);
}
static const struct crypto_type crypto_scomp_type = {
.extsize = crypto_alg_extsize,
.init_tfm = crypto_scomp_init_tfm,
#ifdef CONFIG_PROC_FS
.show = crypto_scomp_show,
#endif
.report = crypto_scomp_report,
.maskclear = ~CRYPTO_ALG_TYPE_MASK,
.maskset = CRYPTO_ALG_TYPE_MASK,
.type = CRYPTO_ALG_TYPE_SCOMPRESS,
.tfmsize = offsetof(struct crypto_scomp, base),
};
int crypto_register_scomp(struct scomp_alg *alg)
{
struct crypto_alg *base = &alg->base;
base->cra_type = &crypto_scomp_type;
base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
base->cra_flags |= CRYPTO_ALG_TYPE_SCOMPRESS;
return crypto_register_alg(base);
}
EXPORT_SYMBOL_GPL(crypto_register_scomp);
int crypto_unregister_scomp(struct scomp_alg *alg)
{
return crypto_unregister_alg(&alg->base);
}
EXPORT_SYMBOL_GPL(crypto_unregister_scomp);
int crypto_register_scomps(struct scomp_alg *algs, int count)
{
int i, ret;
for (i = 0; i < count; i++) {
ret = crypto_register_scomp(&algs[i]);
if (ret)
goto err;
}
return 0;
err:
for (--i; i >= 0; --i)
crypto_unregister_scomp(&algs[i]);
return ret;
}
EXPORT_SYMBOL_GPL(crypto_register_scomps);
void crypto_unregister_scomps(struct scomp_alg *algs, int count)
{
int i;
for (i = count - 1; i >= 0; --i)
crypto_unregister_scomp(&algs[i]);
}
EXPORT_SYMBOL_GPL(crypto_unregister_scomps);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Synchronous compression type");
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