Date: Tue, 21 Sep 2010 10:09:28 +0300 From: Andriy Gapon <avg@freebsd.org> To: Jeff Roberson <jroberson@jroberson.net> Cc: Andre Oppermann <andre@freebsd.org>, Jeff Roberson <jeff@freebsd.org>, Robert Watson <rwatson@freebsd.org>, freebsd-hackers@freebsd.org Subject: Re: zfs + uma Message-ID: <4C985A28.6050706@freebsd.org> In-Reply-To: <alpine.BSF.2.00.1009202037260.23448@desktop> References: <4C93236B.4050906@freebsd.org> <4C935F56.4030903@freebsd.org> <alpine.BSF.2.00.1009181221560.86826@fledge.watson.org> <alpine.BSF.2.00.1009181135430.23448@desktop> <4C95C804.1010701@freebsd.org> <alpine.BSF.2.00.1009182225050.23448@desktop> <4C95CCDA.7010007@freebsd.org> <4C984E90.60507@freebsd.org> <alpine.BSF.2.00.1009202037260.23448@desktop>
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on 21/09/2010 09:39 Jeff Roberson said the following: > I'm afraid there is not enough context here for me to know what 'the same > mechanism' is or what solaris does. Can you elaborate? This was in my first post: [[[ There is this good book: http://books.google.com/books?id=r_cecYD4AKkC&printsec=frontcover Please see section 6.2.4.5 on page 225 and table 6-11 on page 226. And also this code: http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/common/os/kmem.c#971 ]]] > I prefer not to take the weight of specific examples too heavily when > considering the allocator as it must handle many cases and many types of > systems. I believe there are cases where you want large allocations to be > handled by per-cpu caches, regardless of whether ZFS is one such case. If ZFS > does not need them, then it should simply allocate directly from the VM. > However, I don't want to introduce some maximum constraint unless it can be > shown that adequate behavior is not generated from some more adaptable algorithm. Yes, I agree in general. But sometimes simplicity has its benefits too as opposed to complex dynamic behavior that _might_ result from adaptive algorithms. Anyway, I have some early patches to implement first two of your suggestions and I am testing them now. Looks good to me so far. Parameters in the adaptions would probably need some additional tuning. -- Andriy Gapon
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