On Thu, 2011-01-20 at 08:45 -0800, Greg KH wrote:

On Thu, Jan 20, 2011 at 10:36:40AM -0600, Nathan Fontenot wrote:

quoted

The root of this issue is in sysfs directory creation. Every time
a directory is created a string compare is done against sibling
directories ( see sysfs_find_dirent() ) to ensure we do not create 
duplicates.  The list of directory nodes in sysfs is kept as an
unsorted list which results in this being an exponentially longer
operation as the number of directories are created.

Again, are you sure about this?  I thought we resolved this issue in the
past, but you were going to check it.  Did you?

Just to be clear, simply reducing the number of kobjects can make these
patches worthwhile on their own.  I originally figured that the
SECTION_SIZE would go up over time as systems got larger, and _that_
would keep the number of sections and number of sysfs objects down.
Well, that turned out to be wrong, and we're eating up a ton of memory
now.  We can't fix the SECTION_SIZE easily, but we can reduce the number
of kobjects that we need to track the sections.  *That* is the main
benefit I see from these patches.

I think there's a problem worth fixing, even ignoring the directory
creation issue (if it still exists).

-- Dave

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>