Messages in this thread | | | Date | Thu, 2 Oct 2014 23:06:39 +0300 | From | Alexey Dobriyan <> | Subject | Re: [RFC PATCH linux 2/2] fs/proc: use a hash table for the directory entries |
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On Thu, Oct 02, 2014 at 11:01:50AM -0700, Eric W. Biederman wrote: > Nicolas Dichtel <nicolas.dichtel@6wind.com> writes: > > > From: Thierry Herbelot <thierry.herbelot@6wind.com> > > > > The current implementation for the directories in /proc is using a single > > linked list. This is slow when handling directories with large numbers of > > entries (eg netdevice-related entries when lots of tunnels are opened). > > > > This patch enables multiple linked lists. A hash based on the entry name is > > used to select the linked list for one given entry. > > > > The speed creation of netdevices is faster as shorter linked lists must be > > scanned when adding a new netdevice. > > Is the directory of primary concern /proc/net/dev/snmp6 ? > > Unless I have configured my networking stack weird by mistake that > is the only directory under /proc/net that grows when we add an > interface. > > I just want to make certain I am seeing the same things that you are > seeing. > > I feel silly for overlooking this directory when the rest of the > scalability work was done.
Slowdown comes from "duplicate name" check:
for (tmp = dir->subdir; tmp; tmp = tmp->next) if (strcmp(tmp->name, dp->name) == 0) { WARN(1, "proc_dir_entry '%s/%s' already registered\n", dir->name, dp->name); break; }
Removal can be made O(1) after switching to doubly-linked list.
Alexey
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