On 9/15/2010 4:51 PM, Martin Langhoff wrote: > On Wed, Sep 15, 2010 at 10:14 PM, James Cameron<[email protected]> wrote: >> For interest, I've compared the time it takes to fs-update using >> OpenFirmware versus a Linux kernel and shell mediated installation >> method. > Why not compared to (linux-based) dd?
Because I did not want to write blocks that did not need to be written. Both dd and fs-update write everything. What is interesting about the filesystem result is that it takes longer despite writing far less data; 1.6 GB out of 4 GB. And there was no ext3 journal involved during the write. > That'd be more fair I wasn't trying to be fair, I was trying to win. > and gives the linux kernel an opportunity to show us whether better IO > scheduling helps, without gains being clobbered by FS. Test completed, but fs-update still wins. fs-update takes 00:19:42, and dd takes 00:20:46 without fdatasync, and 00:20:51 with fdatasync. At least these results are close. Here are the results in more detail, again with a USB HDD booted using the OLPC kernel, and a 4 GB microSD: 1. baseline timings 04:48 dd if=q of=/dev/null bs=65536 09:35 dd if=/dev/mmcblk0 of=/dev/null bs=65536 2. reading from internal microSD 09:46 dd if=/dev/mmcblk0 of=q bs=65536 09:58 dd if=/dev/mmcblk0 of=q bs=65536 conv=fdatasync 3. writing to internal microSD 19:42 fs-update 20:46 dd if=q of=/dev/mmcblk0 bs=65536 20:51 dd if=q of=/dev/mmcblk0 bs=65536 conv=fdatasync Experiments were also conducted with iflag=direct, oflag=direct, and oflag=nonblock. No useful results. They all acted to slow it down. -- James Cameron http://quozl.linux.org.au/ _______________________________________________ Devel mailing list [email protected] http://lists.laptop.org/listinfo/devel
