Date: Tue, 3 Jul 2007 18:15:41 -0700 (PDT) From: Jeff Roberson <jroberson@chesapeake.net> To: arch@freebsd.org Subject: Re: Fine grain select locking. Message-ID: <20070703181242.T552@10.0.0.1> In-Reply-To: <20070702230728.E552@10.0.0.1> References: <20070702230728.E552@10.0.0.1>
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Here is an update that avoids the malloc per fd when there are no collisions. This unfortunately adds 64bytes to every socket in the system. This is less than 10% of the size of the socket. Vnodes only allocate their selinfo structures on demand so this does not cause a per-file overhead. This was suggested by Peter. This patch also uses a vm zone for the selfd structures. I can shrink them slightly by using a SLIST in one case vs TAILQ as well. http://people.freebsd.org/~jeff/select2.diff Thanks, Jeff On Mon, 2 Jul 2007, Jeff Roberson wrote: > I have a diff which makes the following improvements to select: > > 1) Per-thread wait channel rather than global select wait channel. > 2) Per-thread select lock. > 3) Rescan after sleep scans only descriptors which have come active. > 4) No exposed select internals. > 5) selwakeuppri() works again. > 6) No thread_lock()ing in select, no TDF_SELECT required. > 7) No more collisions. > > This is based on an approach from Alfred with some locking and rescan > improvements by me. It only required changing select users in cases where > they assumed only one thread could select at a time. > > The unfortunate cost of this patch is that a descriptor per select fd must be > allocated to track individual threads. This is what allows us to know which > descriptor has fired an event and allows us to use per-thread locking etc. > > The one thing I haven't fixed is netsmb and netncp which both have some wonky > select implementation that could be replaced with kern_select(). That could > be done seperately from this patch but is required for this to go in. > > http://people.freebsd.org/~jeff/select.diff > > Comments and suggestions welcome. > > Thanks, > Jeff > _______________________________________________ > freebsd-arch@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-arch > To unsubscribe, send any mail to "freebsd-arch-unsubscribe@freebsd.org" >
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