Date: Sun, 7 Sep 2014 16:56:49 +0400 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Andriy Gapon <avg@FreeBSD.org> Cc: src-committers@FreeBSD.org, John Baldwin <jhb@FreeBSD.org>, Peter Wemm <peter@wemm.org>, Alan Cox <alc@rice.edu>, svn-src-all@FreeBSD.org, Dmitry Morozovsky <marck@rinet.ru>, "Matthew D. Fuller" <fullermd@over-yonder.net>, Steven Hartland <killing@multiplay.co.uk>, svn-src-head@FreeBSD.org, Nikolai Lifanov <lifanov@mail.lifanov.com> Subject: Re: svn commit: r270759 - in head/sys: cddl/compat/opensolaris/kern cddl/compat/opensolaris/sys cddl/contrib/opensolaris/uts/common/fs/zfs vm Message-ID: <20140907125649.GA72244@zxy.spb.ru> In-Reply-To: <5409810E.1080705@FreeBSD.org> References: <201408281950.s7SJo90I047213@svn.freebsd.org> <169C94ED141B435BACEADB04A4824717@multiplay.co.uk> <54072E20.10802@mail.lifanov.com> <2230377.GgKARkJyaG@ralph.baldwin.cx> <540778A2.3080809@mail.lifanov.com> <5407816B.9000401@FreeBSD.org> <86292055B4114529874B693EEB441CB6@multiplay.co.uk> <5409810E.1080705@FreeBSD.org>
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On Fri, Sep 05, 2014 at 12:23:26PM +0300, Andriy Gapon wrote: > on 04/09/2014 04:18 Steven Hartland said the following: > > Indeed that would be interesting, but we might find that its quite memory size > > dependent given the scaling so confirming HW details would be nice too. > > > > I'd also be interested to know who wins the free race between the VM and ARC > > when using that value. > > BTW, I've written a small silly program that tests for a problem that affected > me in the distant past: http://people.freebsd.org/~avg/arc-vs-swap.c > > It gobbles almost all of the memory and then just sits on it never accessing it > again. At the same time it repeatedly reads blocks of data from a large file. > The idea is that eventually the unused memory should be pushed out to the swap > and the ARC is allowed to grow to accommodate for the data being read. > > I run this program on a freshly booted system without any other applications. > Prior to r270759 the system behaves as expected. Although the pace of shifting > balance between the ARC and the swap-backed pages is quite slow. > After r270759 and with the default tuning the ARC always sits at its minimum > size. To me this is a regression. > > To summarize: I really appreciate the improvements that you are making here > https://reviews.freebsd.org/D702 > Thanks! > > P.S. > I wish there was an easy way to make the page cache and the ARC aware of each other. I think no single way for any workload. For some workloads ARC is prefered. For some -- RSS is prefered. May be need some tunable for elastics factor ARC/RSS? PS: very bad that 'data limit' don't anymore reflect application memory consumer. and very small application can adapt to 'no memory' from system.
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