Date: Mon, 22 Dec 2014 10:42:49 -0800 From: Adrian Chadd <adrian@freebsd.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, Andriy Gapon <avg@freebsd.org>, John Baldwin <jhb@freebsd.org> Subject: Re: svn commit: r276008 - in head/sys: kern sys Message-ID: <CAJ-Vmo=gNeCTKr9Em05O0Bs=8Oj5KeRAbsDRwCUcTgb8csJVEA@mail.gmail.com> In-Reply-To: <20141222172810.GY2148@kib.kiev.ua> References: <201412211332.sBLDW8VC030548@svn.freebsd.org> <20141221151425.GX2148@kib.kiev.ua> <5496F37D.5030903@FreeBSD.org> <201412220940.02509.jhb@freebsd.org> <20141222172810.GY2148@kib.kiev.ua>
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On 22 December 2014 at 09:28, Konstantin Belousov <kostikbel@gmail.com> wrote: > On Mon, Dec 22, 2014 at 09:40:02AM -0500, John Baldwin wrote: >> On Sunday, December 21, 2014 11:21:17 am Andriy Gapon wrote: >> > On 21/12/2014 17:14, Konstantin Belousov wrote: >> > > On Sun, Dec 21, 2014 at 04:45:28PM +0200, Andriy Gapon wrote: >> > >> On 21/12/2014 16:41, Konstantin Belousov wrote: >> > >>> Or, are you asking why caching of the name could be needed for >> > >>> core dump files at all ? >> > >> >> > >> Sort of. Why VN_OPEN_NAMECACHE is useful in the case of core dumps? >> > >> What does it make better? >> > > The vn_fullpath() mostly works for the core files after the change, >> > > comparing with the non-working state at all before. >> > > >> > >> > Ah, vn_fullpath(). Thank you. >> >> Is there something specific to core dumps that makes vn_fullpath() more >> useful to have working before a process tries to open the core? (As >> compared to other newly-created files) > > See other Rui' reply in the thread. It was done by his request. > > Basically, we cannot enable caching for CREATE, since operations like > extracting large archive, would flush the cache. Doing it rarely > and when needed is acceptable. The explained use case seems to > be warranted. .. 2c, sounds like having an ARC style replacement policy for namecache entries would be useful. (I mean the policy as described in the ARC paper, not the ZFS implementation as a block cache.) -adrian
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