Messages in this thread | | | Date | Sat, 8 Apr 2006 16:47:18 +0200 | From | "Alessandro Suardi" <> | Subject | 40% IDE performance regression going from FC3 to FC5 with same kernel |
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I'll be filing a FC5 performance bug for this but would like an opinion from the IDE kernel people just in case this has already been seen...
I just upgraded my home K7-800, 512MB RAM box from FC3 to FC5 and noticed a disk performance slowdown while copying files around.
System has two 160GB disks, a Samsung SP1604N 2MB cache and a Maxtor 6Y160P0 8MB cache; both disks appear to be almost 2x slower both on hdparm -t tests (17-19MB/s against 33/35 MB/s) and on dd tests, like this:
FC3 [root@donkey tmp]# time dd if=/dev/hda of=/dev/null skip=200 bs=1024k count=200 200+0 records in 200+0 records out
real 0m4.623s user 0m0.004s sys 0m1.308s
FC5 [root@donkey tmp]# time dd if=/dev/hda of=/dev/null skip=200 bs=1024k count=200 200+0 records in 200+0 records out 209715200 bytes (210 MB) copied, 9.67808 seconds, 21.7 MB/s
real 0m9.683s user 0m0.008s sys 0m1.400s
The initial tests were my last FC3 self-compiled kernel (2.6.16-rc5-git8) vs FC5's 2.6.16-1.2080_FC5 kernel; so just to be sure, I copied over from my FC3 partition the 2.6.16-rc5-git8 kernel and its config file, and rebuilt it under FC5, with just a few differences for the new USB 2.0 disk I added to a PCI controller I just put in, namely
[root@donkey linux-2.6.16-rc5-git8]# diff .config /fc3/usr/src/linux-2.6.16-rc5-git8/.config 4c4 < # Fri Apr 7 03:58:23 2006 --- > # Mon Mar 6 22:49:32 2006 1110,1112c1110 < CONFIG_USB_EHCI_HCD=m < CONFIG_USB_EHCI_SPLIT_ISO=y < CONFIG_USB_EHCI_ROOT_HUB_TT=y --- > # CONFIG_USB_EHCI_HCD is not set 1115c1113 < CONFIG_USB_UHCI_HCD=m --- > CONFIG_USB_UHCI_HCD=y 1218d1215 < # CONFIG_USB_SISUSBVGA is not set
The result is unexpected - performance delta is still there. Concatenating output from hdparm -i /dev/hda and hdparm /dev/hda for the same kernel under FC3 and FC5, the only difference is
[root@donkey ~]# diff /tmp/hdparm.out.2616rc2git8-fc5 /tmp/hdparm.out.2616rc2git8 14c14 < Drive conforms to: (null): ATA/ATAPI-1 ATA/ATAPI-2 ATA/ATAPI-3 ATA/ATAPI-4 ATA/ATAPI-5 ATA/ATAPI-6 ATA/ATAPI-7 --- > Drive conforms to: (null): 27c27 < geometry = 19457/255/63, sectors = 312581808, start = 0 --- > geometry = 19457/255/63, sectors = 160041885696, start = 0
I'll try now and rebuild a 2.6.16-rc5-git8 kernel under FC5 with the FC3 GCC and see whether that is responsible for the performance drop... of course if anyone has any idea about what's going on, I will be happy to try out stuff. Attaching hdparm output from the FC5 2.6.16-rc5-git8 just to show that there is DMA etc. all configured fine.
Thanks in advance, ciao,
--alessandro
"Dreamer ? Each one of us is a dreamer. We just push it down deep because we are repeatedly told that we are not allowed to dream in real life" (Reinhold Ziegler) [unhandled content-type:application/octet-stream] | |