141816 – ttyACM extremely slow with 2.6.17-gentoo-r4

Bug 141816 - ttyACM extremely slow with 2.6.17-gentoo-r4

Summary: ttyACM extremely slow with 2.6.17-gentoo-r4

Status:	RESOLVED NEEDINFO

Alias:	None

Product:	Gentoo Linux
Classification:	Unclassified
Component:	[OLD] Core system (show other bugs)
Hardware:	x86 Linux

Importance:	High normal (vote)
Assignee:	Gentoo Kernel Bug Wranglers and Kernel Maintainers

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Depends on:
Blocks:

Reported:	2006-07-26 12:20 UTC by Jiri Pittner
Modified:	2006-09-04 11:27 UTC (History)
CC List:	0 users

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Runtime testing required:	---

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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