Date: Sat, 17 Nov 2007 10:29:18 +0100 From: "Ivan Voras" <ivoras@freebsd.org> To: "Bruce Cran" <bruce@cran.org.uk> Cc: Laszlo Nagy <gandalf@shopzeus.com>, freebsd-questions@freebsd.org Subject: Re: How to set maximum disk cache size? Message-ID: <9bbcef730711170129t5af29c81u6442e1d6ba8c8b47@mail.gmail.com> In-Reply-To: <473E2FAA.2050607@cran.org.uk> References: <473C7C0A.4060708@shopzeus.com> <20071115182220.E60452@wojtek.tensor.gdynia.pl> <473CAF70.1090006@cran.org.uk> <fhk6pp$6fm$1@ger.gmane.org> <473DC14D.1060601@shopzeus.com> <9bbcef730711160829s186d0784g8546c2656f913c0f@mail.gmail.com> <473E2FAA.2050607@cran.org.uk>
next in thread | previous in thread | raw e-mail | index | archive | help
On 17/11/2007, Bruce Cran <bruce@cran.org.uk> wrote: > Ivan Voras wrote: > > On 16/11/2007, Laszlo Nagy <gandalf@shopzeus.com> wrote: > >> Ivan Voras wrote: > > > >>> http://www.freebsd.org/doc/en_US.ISO8859-1/books/arch-handbook/vm-fileio.html > >>> > >> I read this too but I don't understand. Too difficult for me. > >> > >> So what is the answer? Do I need to set a sysctl or will FreeBSD use all > >> available free memory for caching file data from disk? > > > > You don't need to change anything, it's the default state. > > So as long as the memory isn't shown as "Free" in top, any memory that > isn't being used by the kernel or by applications is being used for > cache/buffer? Yes. > One reason why I had thought that FreeBSD didn't use all > the memory for caching disk accesses was because I saw a different > behaviour when decompressing large archives between Linux and FreeBSD: > in Linux there's a massive burst of activity as the archive gets put > straight into memory; then, once memory starts getting full it pauses > for what seems a very long time as it flushes all the data to disk. > FreeBSD doesn't seem to do that; it seems a lot smoother in that it > writes to the disk a lot more regularly - is this likely to be because > Linux has a higher limit on the number of dirty pages it can have in > memory before it writes them out to disk? Yes.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?9bbcef730711170129t5af29c81u6442e1d6ba8c8b47>