On Thu, 2005-08-18 at 17:15 -0400, Adam Goode wrote: > On Thu, 2005-08-18 at 22:49 +0200, Pavel Machek wrote: > > Please make it "echo 1 > frozen", then userspace can do "echo 0 > frozen" > > after five seconds. > > What if the code to do "echo 0 > frozen" is swapped out to disk? ;)
In the real world, to be really sure that you're not doing a trip out to the disk, you'll need a daemon which doesn't do any allocations between when it's notified and when it does the write to the control file. In reality, that probably means a statically compiled daemon that mlock()s itself, and any structures that it will need. It _might_ even need to keep an open file descriptor on the "frozen" file. Because, in theory, that file could be written out to the sysfs backing store. -- Dave - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/