ext3 peformance problem
liuyue
liuyue at ncic.ac.cn
Thu Dec 27 06:30:46 UTC 2007
ext3-usershello all,
I am testing ext3 file system recently but find some problem
I use GreatTurbo Enterprise Server 10 (Zuma) and 2.6.20 kernel
I conducted my test as follows:
mkfs.ext3 /dev/sdb1
mount /dev/sdb1 /mnt/test
cd /mnt/test
mkdir 0 1 2 3 4 5 6 7
I test write and read performance under different subdirs and give the performance result. I also use filefrag to see the file layout.
Command line used: /root/iozone -s 5g -r 1m -i 0 -i 1 -f /mnt/test/0/tmpfile -c -e -+n -w
5242880 1024 72706 0 80474 0
/mnt/test/0/tmpfile: 44 extents found, perfection would be 41 extents
Command line used: /root/iozone -s 5g -r 1m -i 0 -i 1 -f /mnt/test/1/tmpfile -c -e -+n -w
5242880 1024 49957 0 52899 0
/mnt/test/1/tmpfile: 42 extents found, perfection would be 41 extents
Command line used: /root/iozone -s 5g -r 1m -i 0 -i 1 -f /mnt/test/2/tmpfile -c -e -+n -w
5242880 1024 60292 0 64664 0
/mnt/test/2/tmpfile: 42 extents found, perfection would be 41 extents
Command line used: /root/iozone -s 5g -r 1m -i 0 -i 1 -f /mnt/test/3/tmpfile -c -e -+n -w
5242880 1024 70540 0 78644 0
/mnt/test/3/tmpfile: 46 extents found, perfection would be 41 extents
Command line used: /root/iozone -s 5g -r 1m -i 0 -i 1 -f /mnt/test/4/tmpfile -c -e -+n -w
5242880 1024 61334 0 67778 0
/mnt/test/4/tmpfile: 44 extents found, perfection would be 41 extents
Command line used: /root/iozone -s 5g -r 1m -i 0 -i 1 -f /mnt/test/5/tmpfile -c -e -+n -w
5242880 1024 66735 0 75114 0
/mnt/test/5/tmpfile: 42 extents found, perfection would be 41 extents
Command line used: /root/iozone -s 5g -r 1m -i 0 -i 1 -f /mnt/test/6/tmpfile -c -e -+n -w
5242880 1024 65062 0 72686 0
/mnt/test/6/tmpfile: 44 extents found, perfection would be 41 extents
Command line used: /root/iozone -s 5g -r 1m -i 0 -i 1 -f /mnt/test/7/tmpfile -c -e -+n -w
5242880 1024 69247 0 78563 0
/mnt/test/7/tmpfile: 45 extents found, perfection would be 41 extents
Command line used: /root/iozone -s 5g -r 1m -i 0 -i 1 -f /mnt/test/tmpfile -c -e -+n -w
5242880 1024 77085 0 81696 0
Command line used: /root/iozone -s 5g -r 1m -i 0 -i 1 -f /mnt/test/5/tmpfile2 -c -e -+n -w
/mnt/test/5/tmpfile2: 48 extents found, perfection would be 41 extents
5242880 1024 57776 0 64870 0
Command line used: /root/iozone -s 5g -r 1m -i 0 -i 1 -f /mnt/test/5/tmpfile3 -c -e -+n -w
5242880 1024 54799 0 59145 0
/mnt/test/5/tmpfile3: 44 extents found, perfection would be 41 extents
My questions are:
1. why the performances under different subdirs varies so much? In /mnt/test/0 the performance is 72/80, while in /mnt/test/1 the performance is 49/53
2. I see that the extents of all files are nearly the same, but their performances are different. What are the other factors that influence the performance except for the extents(fragmentation) of the file?
3. Is it true that the more files there already exists in a dir, the lower performance we will get if we test under the dir?
as in my test, the performance of /mnt/test/5/tmpfile is 66/75, while the performances of /mnt/test/5/tmpfile2 and tmpfile3 are 57/64 54/59
Thanks very much
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