Re: [PATCH]generic usb serial driver
Pete Zaitcev <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Organization | Red Hat, Inc. |
| Message-ID | <[email protected]> |
On Fri, 30 Mar 2007 20:33:10 +0200, Oliver Neukum <[email protected]> wrote: > Am Freitag, 30. März 2007 19:56 schrieb Greg KH: > > > The bottom line is, there's no excuse for using any kind of smp_mb() > > > in USB drivers. None at all. When we have 100Gbit/s USB, then perhaps > > > we can talk about it. > > > > Perhaps then, but even then, I doubt it... > > That's not the issue. The question is not what we USB needs in terms > of performance. Every time we use a lock we screw anybody caring about > interrupt latency. The amount of work some drivers do in irq is awful. That's true, I suppose. What do you think about bumping some processing to tasklets? Softirqs are a tried technique, I used it back in 1985. Changing ub to relax its locking from spin_lock_irqsave to spin_lock_bh is on my todo list. This, however, introduces some fragility. E.g. how do you lock against timers. -- Pete ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel