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SubjectRe: [Ext2-devel] Re: [PATCH] concurrent block allocation for ext2 against 2.5.64
From
Date
>>>>> Andrew Morton (AM) writes:

AM> Nope. What we're trying to measure here is pure in-memory lock
AM> contention, locked bus traffic, context switches, etc, etc. To
AM> do that we need to get the IO system out of the picture.

I simple use own pretty simple test. btw, you may disable preallocation
to increase allocation rate


bash-script:
============================================================
#!/bin/sh

# args:
# 1 - how many processes to create
# 2 - how many blocks in file to be written
# 3 - how many times to repeat (write+truncate)
# for example: cd.sh 2 32 100000

let i=0
while let "i < $1"; do
if [ ! -d /mnt/$i ]; then
mkdir /mnt/$i
fi
rm -rf /mnt/$i/*
let "i=i+1"
done

sync
sync

let i=0
while let "i < $1"; do
time /root/cdsingle $2 $3 /mnt/$i/1 &
let "i=i+1"
done

wait
============================================================

C programm, which does loop over writes and truncate:

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>


main (int argc, char ** argv)
{
int i, j, num, siz, err, k;
int fd[1024];

num = atoi(argv[2]);
siz = atoi(argv[1]);

for (i = 3; i < argc; i++) {
fd[i] = creat(argv[i], 0666);
if (fd[i] < 0) {
perror("can't create");
exit(1);
}
}

for (j = 0; j < num; j++) {
for (i = 3; i < argc; i++) {
for (k = 0; k < siz; k++)
if ((err = write(fd[i], main, 4096)) < 0) {
printf("err=%d\n", err);
perror("can't write");
exit(1);
}
}
for (i = 3; i < argc; i++) {
ftruncate(fd[i], 0);
lseek(fd[i], 0, SEEK_SET);
}
}

for(i = 3; i < argc; i++) {
close(fd[i]);
if (unlink(argv[i]) < 0)
perror("can't unlink");
}
}


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