Messages in this thread | | | Date | Mon, 6 Oct 2003 23:01:11 +0530 | From | Dipankar Sarma <> | Subject | Re: [RFC 0/6] Backing Store for sysfs |
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On Mon, Oct 06, 2003 at 09:08:46AM -0700, Greg KH wrote: > On Mon, Oct 06, 2003 at 02:29:15PM +0530, Maneesh Soni wrote: > > > > 2.6.0-test6 With patches. > > ----------------- > > dentry_cache (active) 2520 2544 > > inode_cache (active) 1058 1050 > > LowFree 875032 KB 874748 KB > > So with these patches we actually eat up more LowFree if all sysfs > entries are searched, and make the dentry_cache bigger? That's not good :(
My guess is that those 24 dentries are just noise. What we should do is verify with a large number of devices if the numbers are all that different after a walk of the sysfs tree.
> > Remember, every kobject that's created will cause a call to > /sbin/hotplug which will cause udev to walk the sysfs tree to get the > information for that kobject. So I don't see any savings in these > patches, do you?
Assuming that unused files/dirs are aged out of dentry and inode cache, it should benefit. The numbers you should look at are -
-------------------------------------------------------- After mounting sysfs ------------------- dentry_cache (active) 2350 1321 inode_cache (active) 1058 31 LowFree 875096 KB 875836 KB --------------------------------------------------------
That saves ~800KB. If you just mount sysfs and use a few files, you aren't eating up dentries and inodes for every file in sysfs. How often do you expect hotplug events to happen in a system ? Some time after a hotplug event, dentries/inodes will get aged out and then you should see savings. It should greatly benefit in a normal system.
Now if the additional kobjects cause problems with userland hotplug, then that needs to be resolved. However that seems to be a different problem altogether. Could you please elaborate on that ?
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