./memstream2 512
testing mem stream, block size 536870912...
zsh: killed ./memstream2 512
dmesg: Out of Memory: Killed process 28142 (memstream2).
vherva@whale:/home/vherva/scratch>free
total used free shared buffers cached
Mem: 2057888 1353744 704144 0 63904 1100480
-/+ buffers/cache: 189360 1868528
Swap: 255984 166528 89456
vherva@whale:/home/vherva/scratch>cat /proc/slabinfo
slabinfo - version: 1.1 (SMP)
kmem_cache 111 111 432 3 3 1 : 124 62
ip_fib_hash 10 454 32 1 1 1 : 252 126
urb_priv 1 123 128 1 1 1 : 252 126
journal_head 255 354 88 2 2 1 : 252 126
revoke_table 2 816 16 1 1 1 : 252 126
revoke_record 0 0 64 0 0 1 : 252 126
clip_arp_cache 0 0 256 0 0 1 : 252 126
ip_mrt_cache 0 0 128 0 0 1 : 252 126
tcp_tw_bucket 0 0 128 0 0 1 : 252 126
tcp_bind_bucket 20 240 64 1 1 1 : 252 126
tcp_open_request 0 0 128 0 0 1 : 252 126
inet_peer_cache 1 123 128 1 1 1 : 252 126
ip_dst_cache 49 310 256 5 5 1 : 252 126
arp_cache 6 166 192 2 2 1 : 252 126
blkdev_requests 512 581 192 7 7 1 : 252 126
dnotify cache 0 0 40 0 0 1 : 252 126
file lock cache 2 198 160 2 2 1 : 252 126
fasync cache 1 582 24 1 1 1 : 252 126
uid_cache 2 240 64 1 1 1 : 252 126
skbuff_head_cache 439 496 256 8 8 1 : 252 126
sock 230 230 1600 23 23 1 : 60 30
sigqueue 222 348 136 3 3 1 : 252 126
cdev_cache 276 720 64 3 3 1 : 252 126
bdev_cache 6 246 128 2 2 1 : 252 126
mnt_cache 18 246 128 2 2 1 : 252 126
inode_cache 1862 7623 768 363 363 1 : 124 62
dentry_cache 1084 7968 192 96 96 1 : 252 126
dquot 0 0 192 0 0 1 : 252 126
filp 1941 1992 192 24 24 1 : 252 126
names_cache 8 8 4096 2 2 1 : 60 30
buffer_head 289081 360386 192 4339 4342 1 : 252 126
mm_struct 313 372 256 6 6 1 : 252 126
vm_area_struct 4391 4565 192 55 55 1 : 252 126
fs_cache 313 480 64 2 2 1 : 252 126
files_cache 133 133 832 7 7 1 : 124 62
signal_act 110 110 1600 11 11 1 : 60 30
size-131072(DMA) 0 0 131072 0 0 8 : 0 0
size-131072 0 0 131072 0 0 8 : 0 0
size-65536(DMA) 0 0 65536 0 0 4 : 0 0
size-65536 0 0 65536 0 0 4 : 0 0
size-32768(DMA) 0 0 32768 0 0 2 : 0 0
size-32768 3 3 32768 3 3 2 : 0 0
size-16384(DMA) 0 0 16384 0 0 1 : 60 30
size-16384 1 1 16384 1 1 1 : 60 30
size-8192(DMA) 0 0 8192 0 0 1 : 60 30
size-8192 38 68 8192 19 34 1 : 60 30
size-4096(DMA) 0 0 4096 0 0 1 : 60 30
size-4096 220 220 4096 55 55 1 : 60 30
size-2048(DMA) 0 0 2048 0 0 1 : 60 30
size-2048 232 232 2048 29 29 1 : 60 30
size-1024(DMA) 0 0 1024 0 0 1 : 124 62
size-1024 720 720 1024 48 48 1 : 124 62
size-512(DMA) 0 0 512 0 0 1 : 124 62
size-512 186 186 512 6 6 1 : 124 62
size-256(DMA) 0 0 256 0 0 1 : 252 126
size-256 2528 2604 256 42 42 1 : 252 126
size-128(DMA) 1 123 128 1 1 1 : 252 126
size-128 448 738 128 6 6 1 : 252 126
size-64(DMA) 7 240 64 1 1 1 : 252 126
size-64 2442 7200 64 30 30 1 : 252 126
vherva@whale:/home/vherva/scratch>cat memstream2.c
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#define KB (1024)
#define MB (1024 * KB)
#define GB (1024 * MB)
inline unsigned chksum(char* buffer, int len)
{
int i;
unsigned c = 0;
unsigned* ptr;
for (ptr = (unsigned*)buffer; ptr < (unsigned*)&buffer[len]; ptr++)
c += *ptr;
return c;
}
int main(int argc, char** argv)
{
unsigned long blocksz = 64*MB;
unsigned long long streamed = 0, last = 0;
unsigned iter = 0;
unsigned checksum, orig_checksum = 0;
const unsigned long long qgiga = 1024 * 1024 * 1024 / 4;
time_t t = time(NULL);
char *buffer1, *buffer2;
int i;
if (argc > 1) blocksz = atoi(argv[1]) * MB;
fprintf(stderr, "testing mem stream, block size %u...\n\n ", blocksz);
buffer1 = malloc(blocksz + 256);
buffer2 = malloc(blocksz + 256);
if (!buffer1 || !buffer2)
{
perror("malloc failed");
exit(1);
}
for (i = 0; i < blocksz; i++)
buffer1[i] = (i + rand()) % 256;
orig_checksum = chksum(buffer1, blocksz);
memcpy(buffer2, buffer1, blocksz);
while (1)
{
int times = 8;
unsigned checksum1, checksum2;
for (i = 0; i < times; i++)
{
checksum1 = chksum(buffer1, blocksz);
checksum2 = chksum(buffer2, blocksz);
if (orig_checksum != checksum2 || checksum1 != checksum2)
{
fprintf(stderr, "Blocks differ! %x, %x\n", checksum, orig_checksum);
fprintf(stderr, "Read the blocks %i time (streamed %llu bytes.)\n", (iter * times + i * 2), streamed + blocksz * i * 2);
exit(-1);
}
}
streamed += blocksz * times * 2;
if (streamed - last > qgiga)
{
fprintf(stderr, "\010\010\010\010\010\010\010\010\010\010.%6.1fMB/s",
(float)(streamed - last) / (float)(time(NULL) - t) / (float)MB);
t = time(NULL);
last = streamed;
}
iter++;
}
return 0;
}
I tried to reproduce with a simpler program:
#include <stdio.h>
#include <stdlib.h>
#define BKSP "\010\010\010\010\010\010"
int main(int argc, char** argv)
{
unsigned long megs = 512;
unsigned long size, i;
unsigned char* buf;
if (argc > 1) megs = atol(argv[1]);
size = megs * 1024 * 1024;
fprintf(stderr, "Allocating %lu megs...\n\n ", megs);
buf = malloc(size);
for (i = 0; i < size; i++)
{
buf[i] = 42;
if ((i + 1) % (1024 * 1024) == 0)
fprintf(stderr, BKSP "%4uMB", (i + 1) / 1024 / 1024);
}
fprintf(stderr, "\n Success.\n");
return 1;
}
I didn't get killed even with 1536 yet, but it basically halts at 1200+
megs:
./alloc 1536
Allocating 1536 megs...
1263MB
<hangs there making very little progress>
free
total used free shared buffers cached
Mem: 2057888 2051280 6608 0 63280 665296
-/+ buffers/cache: 1322704 735184
Swap: 255984 255984 0
5 root 12 0 0 0 0 SW 88.9 0.0 5:29 kswapd
28312 vherva 20 0 1385M 1.3G 784 R 88.2 16.0 4:21 alloc
So again, releaseing cache seems to be the culprit.
I can try -aa if you think it's worth it.
-- v --
v@iki.fi
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