Date: Thu, 10 Jun 2010 13:36:29 -0400 From: Gary Palmer <gpalmer@freebsd.org> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: freebsd-fs@FreeBSD.org, Anders Nordby <anders@FreeBSD.org> Subject: Re: Odd network issues on ZFS based NFS server Message-ID: <20100610173629.GA70716@in-addr.com> In-Reply-To: <20100610114614.GA71432@icarus.home.lan> References: <20100608083649.GA77452@fupp.net> <Pine.GSO.4.63.1006081946040.8742@muncher.cs.uoguelph.ca> <20100609122517.GA16231@fupp.net> <Pine.GSO.4.63.1006091119410.23896@muncher.cs.uoguelph.ca> <20100610111316.GB87243@fupp.net> <20100610114614.GA71432@icarus.home.lan>
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On Thu, Jun 10, 2010 at 04:46:14AM -0700, Jeremy Chadwick wrote: > Clarification: I believe it actually has 1927MB (147M Inact + 1780M > Free) available. I've always understood top's "Free" field to mean > "number/amount of pages which have never been touched/used since the > kernel was started", while "Inact" to mean "number/amount of pages which > have been touched/used but are not actively being used, this available > for use". > > If someone more familiar with the VM and top could expand on this, > that'd be helpful. I'm not a VM guru, however here is my understanding: - "Free" are pages that have been reclaimed by the page daemon and are ready for immediate use without further action. The page daemon always tries to keep a few pages in the "Free" state to avoid problems with page starvation - "Inactive" pages are pages that are candidates for reclamation by the page daemon if so needed. I believe some amount of work is needed to move an inactive page to the free list, including zeroing it I think as well as removing any references still pointing to it (e.g. it could be a cached copy of data from local storage). Probably not completely 100% accurate as I haven't kept up with VM changes in the last few years, but close enough for government work :) Regards, Gary
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