Date: Thu, 29 Jul 2010 15:29:42 +0300 From: Andriy Gapon <avg@icyb.net.ua> To: Alexander Leidinger <Alexander@Leidinger.net> Cc: fs@freebsd.org Subject: Re: arc cache: pagesize and/or power of 2 constraints? Message-ID: <4C517436.7080509@icyb.net.ua> In-Reply-To: <20100729093158.86036msee9pbayw4@webmail.leidinger.net> References: <20100729093158.86036msee9pbayw4@webmail.leidinger.net>
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on 29/07/2010 10:31 Alexander Leidinger said the following: > Hi, > > while writting some acceptance tests for the Solaris machines at work I > wondered if the size of the arc cache should be a multiple of the page > size and/or a power of 2. I searched the net, but was not able to find > some info regarding this. I suppose you mean ZFS ARC, not an ARC concept in general. I wonder why you came at this question. > I would expect that it does not make sense to have an arc cache size > which is not a multiple of the page size. Why? > And depending on how the arc > cache is implemented, it would make sense to have it even as a power of > 2 size (even if it is able to handle non-power-of-2 sizes). Why? > Did someone had a look at this in FreeBSD? ARC size is almost arbitrary. It's a collection of malloc/uma allocated buffers of various sizes, individual sizes are various multiples of 512. -- Andriy Gapon
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