On 06/14/2012 09:26 AM, Alex Shi wrote:
> On 06/14/2012 09:10 AM, Alex Shi wrote:
>
>> On 06/13/2012 10:56 PM, Andi Kleen wrote:
>>
>>> On Tue, Jun 12, 2012 at 05:06:45PM +0800, Alex Shi wrote:
>>>> This patch do flush_tlb_kernel_range by 'invlpg'. The performance pay
>>>> and gain was analysed in my patch (x86/flush_tlb: try flush_tlb_single
>>>> one by one in flush_tlb_range). Now we move this logical into kernel
>>>> part. The pay is multiple 'invlpg' execution cost, that is same. but
>>>> the gain(cost reducing of TLB entries refilling) is absolutely
>>>> increased.
>>>
>>> The subtle point is whether INVLPG flushes global pages or not.
>>> After some digging I found a sentence in the SDM that says it does.
>>> So it may be safe.
>>
>>
>> Many thanks for your time!
>>
>>>
>>> What does it improve?
>>
>>
I just write a rough kernel modules that alloc some page arrays in kernel and then map to vaddr by 'vmap'.
Then my macro benchmark inject a 'unmap_kernel_range' request from a sysfs interface, and doing random memory access in user level during the time.
On my NHM EP 2P * 4 Cores * HT.
Without this patch, the memory access with 4 threads is ~12ns/time.
With this patch, the memory access with 4 threads is ~9ns/time.
With threads number increasing the benefit becomes small and nearly disappeared after thread number up to 256.
But no any regression.
The rough user macro-benchmark and kernel module is here:
--- kernel module--
#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/gfp.h>
#include <linux/fs.h>
#include <linux/mman.h>
#include <linux/uaccess.h>
#include <linux/sysfs.h>
#include <linux/hrtimer.h>
#include <linux/device.h>
#include <linux/cpu.h>
MODULE_LICENSE("Dual BSD/GPL");
/*
* $cat Makefile
* obj-m := modvmalloc.o
*
* compile command:
* #cd linux; make /home/alexs/exec/modules/modvmalloc.ko
*/
#define NR_PAGES (4)
#define NR_BLOCKS (1024)
struct block {
struct page ** page_array;
void *vaddr;
int page_count;
};
struct block *block;
static int blocks = NR_BLOCKS;
module_param(blocks, uint, 0400);
MODULE_PARM_DESC(blocks, "map unmap blocks number ");
static struct page **relay_alloc_page_array(unsigned int nr_pages)
{
const size_t pa_size = NR_PAGES * sizeof(struct page *);
if (pa_size > PAGE_SIZE)
return vzalloc(pa_size);
return kzalloc(pa_size, GFP_KERNEL);
}
static void relay_free_page_array(struct page **array)
{
if (is_vmalloc_addr(array))
vfree(array);
else
kfree(array);
}
static void vmap_unmap(void)
{
//purge_vmap_area_lazy();
//vm_unmap_aliases();
int i;
for (i=0; i< blocks; i++)
unmap_kernel_range((unsigned long)(block->vaddr), NR_PAGES*PAGE_SIZE);
}
// ---------------
long vmap_num = 0;
static ssize_t __vmap_num_store(const char *buf,
size_t count, int smt)
{
long factor = 0;
long i;
unsigned long start, stop;
if (sscanf(buf, "%ld", &factor) != 1)
return -EINVAL;
vmap_num = factor;
start = ktime_to_ns(ktime_get());
vmap_unmap();
stop = ktime_to_ns(ktime_get());
i = blocks;
printk(KERN_ERR "vunmap %ld times cost %ld ns/time\n",
i, (stop - start)/i);
return count;
}
static ssize_t vmap_num_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return sprintf(buf, "%ld\n", vmap_num);
}
static ssize_t vmap_num_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
return __vmap_num_store(buf, count, 0);
}
DEVICE_ATTR(vmap_num, 0644,
vmap_num_show,
vmap_num_store);
int create_sysfs_vmap_num(struct device *dev)
{
return device_create_file(dev, &dev_attr_vmap_num);
}
static int mapunmap_init(void){
long i,j,k;
create_sysfs_vmap_num(cpu_subsys.dev_root);
block = kmalloc(sizeof(struct block)*blocks, GFP_KERNEL);
for (k=0; k< blocks; k++) {
block[k].page_count = 0;
block[k].page_array = relay_alloc_page_array(NR_PAGES);
if (!block[k].page_array)
return -1;
for (i = 0; i < NR_PAGES; i++) {
block[k].page_array[i] = alloc_page(GFP_KERNEL);
if (unlikely(!block[k].page_array[i])) {
printk(KERN_ERR "\talloc page error \n");
goto depopulate;
}
}
if (i!=NR_PAGES) goto depopulate;
block[k].page_count = i;
block[k].vaddr = vmap(block[k].page_array, NR_PAGES, VM_MAP, PAGE_KERNEL);
if (!(block[k].vaddr)) {
printk(KERN_ERR "\t\t vmap error !\n");
goto depopulate;
}
}
printk(KERN_INFO "vmalloc module init OK \n");
return 0;
depopulate:
for (i=0; i< k; i++)
if (block[i].page_count !=0) {
for (j = 0; j < block[i].page_count; j++)
__free_page((block[j].page_array[j]));
relay_free_page_array(block[j].page_array);
}
printk(KERN_INFO "vmalloc module init fail\n");
return -1;
}
static void mapunmap_exit(void){
long i, j;
printk(KERN_INFO "bye! this is test module\n");
device_remove_file(cpu_subsys.dev_root, &dev_attr_vmap_num);
for (i=0; i< blocks; i++)
if (block[i].page_count !=0) {
for (j = 0; j < block[i].page_count; j++)
__free_page((block[j].page_array[j]));
relay_free_page_array(block[j].page_array);
}
}
module_init(mapunmap_init);
module_exit(mapunmap_exit);
--- benchmark ---
/*
maccess.c
This is a macrobenchmark for TLB flush range testing.
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.
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., 675 Mass Ave, Cambridge, MA 02139, USA.
Copyright (C) Intel 2012
Coypright Alex Shi alex.shi@xxxxxxxxx
gcc -o maccess maccess.c -lrt -lpthread -O2
#perf stat -e r881,r882,r884 -e r801,r802,r810,r820,r840,r880,r807 -e rc01 -e r4901,r4902,r4910,r4920,r4940,r4980 -e r5f01 -e rbd01,rdb20 -e r4f02 -e r8004,r8201,r8501,r8502,r8504,r8510,r8520,r8540,r8580 -e rae01,rc820,rc102,rc900 -e r8600 -e rcb10 ./maccess
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/mman.h>
#include <time.h>
#include <sys/types.h>
#include <pthread.h>
#define FILE_SIZE (1024*1024*1024)
#define PAGE_SIZE (4096)
#define HPAGE_SIZE (4096*512)
#ifndef MAP_HUGETLB
#define MAP_HUGETLB 0x40000
#endif
long getnsec(clockid_t clockid) {
struct timespec ts;
if (clock_gettime(clockid, &ts) == -1)
perror("clock_gettime failed");
return (long) ts.tv_sec * 1000000000 + (long) ts.tv_nsec;
}
//data for threads
struct data{
int pagenum;
void *startaddr;
int rw;
int loop;
};
volatile int * threadstart;
//thread for memory accessing
void *accessmm(void *data){
struct data *d = data;
long *actimes;
char x;
int i, k;
int randn[PAGE_SIZE];
for (i=0;i<PAGE_SIZE; i++)
randn[i] = rand();
actimes = malloc(sizeof(long));
while (*threadstart == 0 )
usleep(1);
if (d->rw == 0)
for (*actimes=0; *threadstart == 1; (*actimes)++)
for (k=0; k < d->pagenum; k++)
x = *(volatile char *)(d->startaddr + randn[k]%FILE_SIZE);
else
for (*actimes=0; *threadstart == 1; (*actimes)++)
for (k=0; k < d->pagenum; k++)
*(char *)(d->startaddr + randn[k]%FILE_SIZE) = 1;
return actimes;
}
int main(int argc, char *argv[])
{
static char optstr[] = "p:w:ht:s:";
int s = 1; /* */
int p = 512; /* default accessed page number, after maccess */
int er = 0, rw = 0, h = 0, t = 2; /* d: debug; h: use huge page; t thread number */
int pagesize = PAGE_SIZE; /*default for regular page */
volatile char x;
long protindex = 0;
int i, j, k, c;
void *m1, *startaddr;
unsigned long *startaddr2[1024*512];
volatile void *tempaddr;
clockid_t clockid = CLOCK_MONOTONIC;
unsigned long start, stop, mptime, actime;
int randn[PAGE_SIZE];
pthread_t pid[1024];
void * res;
struct data data;
char command[1024];
for (i=0;i<PAGE_SIZE; i++)
randn[i] = rand();
while ((c = getopt(argc, argv, optstr)) != EOF)
switch (c) {
case 's':
s = atoi(optarg);
break;
case 'p':
p = atoi(optarg);
break;
case 'h':
h = 1;
break;
case 'w':
rw = atoi(optarg);
break;
case 't':
t = atoi(optarg);
break;
case '?':
er = 1;
break;
}
if (er) {
printf("usage: %s %s\n", argv[0], optstr);
exit(1);
}
printf("pid is %d, thread number %d active %d seconds, access page num %d\n", getpid(), t, s, p);
if (h == 0){
startaddr = mmap(0, FILE_SIZE, PROT_READ|PROT_WRITE, MAP_ANONYMOUS | MAP_SHARED, -1, 0);
pagesize = PAGE_SIZE;
} else {
startaddr = mmap(0, FILE_SIZE, PROT_READ|PROT_WRITE, MAP_ANONYMOUS | MAP_SHARED | MAP_HUGETLB, -1, 0);
pagesize = HPAGE_SIZE;
}
start = getnsec(clockid);
//access whole memory, will generate many page faults
for (tempaddr = startaddr; tempaddr < startaddr + FILE_SIZE; tempaddr += pagesize)
memset((char *)tempaddr, 0, 1);
stop = getnsec(clockid);
threadstart = malloc(sizeof(int));
*threadstart = 0;
data.pagenum = p; data.startaddr = startaddr; data.rw = rw;
for (i=0; i< t; i++)
if(pthread_create(&pid[i], NULL, accessmm, &data))
perror("pthread create");
//wait for randn[] filling.
sleep(1);
mptime = actime = 0;
sprintf(command, "sudo sh -c 'echo %d > /sys/devices/system/cpu/vmap_num'", s);
printf("%s\n", command);
start = getnsec(clockid);
//kick threads, let them running.
*threadstart = 1;
system(command);
*threadstart = 0;
stop = getnsec(clockid);
mptime += stop - start;
//get threads' result.
for (i=0; i< t; i++) {
if (pthread_join(pid[i], &res))
perror("pthread_join");
actime += *(long*)res;
}
end:
printf("maccess %ld ms, memory access %ld times/thread/ms, cost %ldns/time\n",
mptime/1000000, actime*p*1000000/t/mptime, mptime*t/(actime*p));
exit(0);
}
>
>>
>>> -Andi
>>
>>
>
>
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