Kernel Bug Tracker – Bug 5308
Extremely slow UMS write speed under >=2.6.12 kernels on Compaq nx8220 laptop
Last modified: 2005-09-26 02:19:50 UTC
Most recent kernel where this bug did not occur: 188.8.131.52 (not sure: 2.6.9..2.6.11)
Distribution: Slackware 10.2, but i configure and build the kernel with my options
Hardware Environment: Notebook Compaq nx8220 (model )
Software Environment: Slackware 10.2, with my kernel, without third-party patches
Problem Description: Very slow (ca. 50 kbytes/s writing speed when copying files
to my USB Flash) under 184.108.40.206 (and under 2.6.14-rc2-git3). The read speed is
about 8 Mbytes/s. Under 220.127.116.11 is the writing speed ca. 3 Mbytes/s.
The kernels > 18.104.22.168 run unstable on my laptop (see
http://bugzilla.kernel.org/show_bug.cgi?id=5221 ) => i attach here the
22.214.171.124-related logs and config.
I use ehci and uhci modules. With uhci (without ehci) the writing speed is about
The related line in my fstab:
/dev/sda1 /mnt/flash vfat rw,noauto,sync,nosuid,user,noatime
,umask=0,uid=99,gid=99 0 0
Steps to reproduce:
1) Insert usb flash drive under kernel >= 2.6.12.
2) Mount it.
3) Try to copy a large file onto it.
Created attachment 6136 [details]
My kernel .config for 126.96.36.199
The .configs for 188.8.131.52 and 2.6.14-rc2-git3 are based on this config.
Created attachment 6137 [details]
/var/log/debug file, 184.108.40.206
How is it created:
1) Delete an old file
2) Restart system
3) Insert USB Flash
4) Mount it
5) Copy a 45 kb large file on it in mc
6) Unmount it
7) Remove it
Created attachment 6138 [details]
dmesg output, 220.127.116.11
Just compiled the kernel 18.104.22.168. The USB writing speed is OK (about 3 MBytes/s).
Just detected: the writing speed is OK under 22.214.171.124 if no "sync" option in
fstab used for USB flash.
This is a know problem. The problem is that until now, FAT had NEVER cared about
"sync", ie: it didn't work as "sync" even if you passed that option
However, this has been fixed, so when you use sync it really means "sync", so it
gets much slower. You can remove the "sync" option to get more speed
OK, thank you. I will not use "sync" for FAT-volumes more.
*** This bug has been marked as a duplicate of 5258 ***