Date: Wed, 29 Sep 2010 14:41:16 +0200 From: Bas Smeelen <b.smeelen@ose.nl> To: freebsd-questions@freebsd.org Subject: Re: Cache Memory in top command Message-ID: <4CA333EC.40704@ose.nl> In-Reply-To: <20100929124230.00004796@unknown> References: <800348.43799.qm@web113901.mail.gq1.yahoo.com> <AANLkTinxG2k082x=PQoHAq1d8h_Wn0vUwiXO1cssy4Er@mail.gmail.com> <246095.42115.qm@web113905.mail.gq1.yahoo.com> <4CA2E345.7070006@ose.nl> <20100929124230.00004796@unknown>
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On 09/29/2010 01=3A42 PM=2C Bruce Cran wrote=3A =3E On Wed=2C 29 Sep 2010 08=3A57=3A09 +0200 =3E Bas Smeelen =3Cb=2Esmeelen=40ose=2Enl=3E wrote=3A =3E =3E =20 =3E=3E *Cache=3A* number of clean pages caching data that are available fo= r =3E=3E immediate reallocation =3E=3E http=3A//www=2Efreebsd=2Eorg/cgi/man=2Ecgi=3Fquery=3Dtop=26sektion= =3D1 =3E=3E =3Chttp=3A//www=2Efreebsd=2Eorg/cgi/man=2Ecgi=3Fquery=3Dtop=26sektio= n=3D1=3E =3E=3E =20 =3E I believe the =22Cache=22 value is almost totally unrelated to the =3E amount of memory used for caching=3A FreeBSD has a unified buffer cache= =3E so any memory is available for use as cache=2E Unlike Linux=2C you can= =27t =3E look at the line in =27top=27 to see how much memory is being used for= =3E buffers and cache=2E =3E =3E You can find more information about the VM architecture at =3E http=3A//www=2Efreebsd=2Eorg/doc/en/books/arch-handbook/vm=2Ehtml =2E= =3E =3E =20 The way I understand it=3A The amount of cached file data pages is included in the Wired value The amount of free cache pages that can immediatly can be re-used for caching is the Cache value The Buf value is the numbder of pages used for BIO-level disk caching I think that the value of Inactive also includes some kind of application data cache So as you also state=2C unlike linux there is no way of determining the amount of memory used for *all caching* with top For more info of basic design decisions I think this is a good resource also=3A http=3A//docs=2Efreebsd=2Eorg/44doc/ DISCLAIMER=3A This e-mail is for the intended recipient=28s=29 only=2E Acce= ss=2C disclosure=2C copying=2C distribution or reliance on any of it by anyone else is prohibited=2E If yo= u have received it by mistake please let us know by reply and then delete it from your system= =2E
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