Date: Mon, 12 Nov 2012 17:10:01 -0600 From: Alan Cox <alc@rice.edu> To: Konstantin Belousov <kostikbel@gmail.com> Cc: alc@freebsd.org, pho@freebsd.org, Sushanth Rai <sushanth_rai@yahoo.com>, StevenSears <Steven.Sears@netapp.com>, "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Re: Memory reserves or lack thereof Message-ID: <50A181C9.7030209@rice.edu> In-Reply-To: <20121112214808.GH73505@kib.kiev.ua> References: <20121112133638.GZ73505@kib.kiev.ua> <1352755682.93266.YahooMailClassic@web181701.mail.ne1.yahoo.com> <20121112214808.GH73505@kib.kiev.ua>
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On 11/12/2012 3:48 PM, Konstantin Belousov wrote: > On Mon, Nov 12, 2012 at 01:28:02PM -0800, Sushanth Rai wrote: >> This patch still doesn't address the issue of M_NOWAIT calls driving >> the memory the all the way down to 2 pages, right ? It would be nice to >> have M_NOWAIT just do non-sleep version of M_WAITOK and M_USE_RESERVE >> flag to dig deep. > This is out of scope of the change. But it is required for any further > adjustements. I would suggest a somewhat different response: The patch does make M_NOWAIT into a "non-sleep version of M_WAITOK" and does reintroduce M_USE_RESERVE as a way to specify "dig deep". Currently, both M_NOWAIT and M_WAITOK can drive the cache/free memory down to two pages. The effect of the patch is to stop M_NOWAIT at two pages rather than allowing it to continue to zero pages. When you say, "This is out of scope ...", I believe that you are referring to changing two pages into something larger. I agree that this is out of scope for the current change. Alan
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