Bug 141816

Summary:	ttyACM extremely slow with 2.6.17-gentoo-r4
Product:	Gentoo Linux	Reporter:	Jiri Pittner <jiri.pittner>
Component:	[OLD] Core system	Assignee:	Gentoo Kernel Bug Wranglers and Kernel Maintainers <kernel>
Status:	RESOLVED NEEDINFO
Severity:	normal
Priority:	High
Version:	1.0
Hardware:	x86
OS:	Linux
Whiteboard:
Package list:		Runtime testing required:	---

Description Jiri Pittner 2006-07-26 12:20:36 UTC

After a kernel update from 2.6.16-gentoo-r12 to 2.6.17-gentoo-r4 I have noticed
an extremely low performance of a CDMA modem using the ttyACM driver. Switching
back to the older kernel returned the performance back to normal. I am using up-to
date gentoo x86 pppd. The cdc-acm.c files differ only by some mutex locking mechanism
between the two kernel versions. The kernel configurations were essentially the same
(make oldconfig). I am using a two-core pentium laptop ACER8204wlmi.

Comment 1 Jakub Moc (RETIRED) gentoo-dev

2006-07-26 12:28:58 UTC

Don' restrict bugs without any reason, please.

Comment 2 Daniel Drake (RETIRED) gentoo-dev

2006-08-21 09:06:29 UTC

Please post "emerge --info" output to every bug that you file.

Can you provide any numbers showing this slowdown?

Can you reproduce this on the latest development kernel, currently 2.6.18-rc4?

Comment 3 Daniel Drake (RETIRED) gentoo-dev

2006-09-04 11:27:15 UTC

see comment #2