Date: Tue, 8 Mar 2016 21:07:46 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Scott Long <scottl@samsco.org> Cc: freebsd-stable@freebsd.org Subject: Re: kernel: mps0: Out of chain frames, consider increasing hw.mps.max_chains. Message-ID: <20160308180746.GE70809@zxy.spb.ru> In-Reply-To: <20160307111012.GL11654@zxy.spb.ru> References: <20160306194555.GC94639@zxy.spb.ru> <0F0C78F4-6FE2-43BA-B503-AA04A79F2E70@samsco.org> <20160306212733.GJ11654@zxy.spb.ru> <DFC3C4CF-89D4-417C-AEBA-67F49F3EA1DE@samsco.org> <20160307060407.GK11654@zxy.spb.ru> <5B8DD95A-9FA0-4E16-85A1-87B54035B3F7@samsco.org> <20160307111012.GL11654@zxy.spb.ru>
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On Mon, Mar 07, 2016 at 02:10:12PM +0300, Slawa Olhovchenkov wrote: > > >>> This allocated one for all controllers, or allocated for every controller? > > >> > > >> It’s per-controller. > > >> > > >> I’ve thought about making the tuning be dynamic at runtime. I > > >> implemented similar dynamic tuning for other drivers, but it seemed > > >> overly complex for low benefit. Implementing it for this driver > > >> would be possible but require some significant code changes. > > > > > > What cause of chain_free+io_cmds_active << max_chains? > > > One cmd can use many chains? > > > > Yes. A request uses and active command, and depending on the size of the I/O, > > it might use several chain frames. I am play with max_chains and like significant cost of handling max_chains: with 8192 system resonded badly vs 2048. Now try 3192, response like with 2048.
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