Messages in this thread | | | Subject | Re: [RFC PATCH] fs: use a sequence counter instead of file_lock in fd_install | From | Eric Dumazet <> | Date | Mon, 20 Apr 2015 10:15:26 -0700 |
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On Mon, 2015-04-20 at 17:10 +0200, Mateusz Guzik wrote:
> Sorry for spam but I came up with another hack. :) > > The idea is that we can have a variable which would signify the that > given thread is playing with fd table in fd_install (kind of a lock > embedded into task_struct). We would also have a flag in files struct > indicating that a thread would like to resize it. > > expand_fdtable would set the flag and iterate over all threads waiting > for all of them to have the var set to 0.
The opposite : you have to block them in some way and add a rcu_sched() or something.
Another way would be to expand the table leaving the old one in place, thanks to a new vrealloc() api. This would require all file tables to at least use one page.
(Instead of use a new set of pages for the new vmalloc()ed area, reuse the pages that are already mapped into previous vmalloc() area.
Right now, expanding 4M slots to 8M slots is taking a long time and is a latency killer.
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