Date: Wed, 21 Apr 2004 13:32:58 -0700 (PDT) From: Julian Elischer <julian@elischer.org> To: Steve Watt <steve@Watt.COM> Cc: hackers@freebsd.org Subject: Re: how to flush out cache.? Message-ID: <Pine.BSF.4.21.0404211331370.31770-100000@InterJet.elischer.org> In-Reply-To: <Pine.BSF.4.21.0404211326301.31770-100000@InterJet.elischer.org>
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On Wed, 21 Apr 2004, Julian Elischer wrote: > > > On Wed, 21 Apr 2004, Steve Watt wrote: > > > In article <Pine.BSF.4.21.0404211219460.31770-100000@InterJet.elischer.org> you write: > > > > > >Ok so I have an application where I need to > > >reread a file I have just written to ensure that it went to disk > > >correctly.. > > > > > >Other than reading a few GB of data, is there a way to flush > > >out the cache copy of a file I've written? > > > > You can flush the file to disk with fsync(). But I don't think that > > evicts the blocks from the cache, just forces them to be written. To > > the disk controller's cache, if you're lucky. > > > > >possibilities include: > > > > > >a file flag saying "don't keep a copy after it's written to disk"? > > >a syscall discard_cached_blocks(fd); Turns out O_DIRECT might do this, but I can't use this as apparently it's being written by a 3rd party program.. I can only check the file after the other program has written it.. > > > > > > > > >? > > >any other suggestions? > > > > What are you hoping to accomplish? There are probably other ways > > to solve the larger problem. > > I thought I was being clear.. > I need to remove all the pages from cache so that a reread of the file > is forced to go to disk. > and I don't want to go read a 2GB dummy file to force the flush.. > > Someone suggested that I read the file usign 'dump' through the raw > device.. > > > > > > -- > > Steve Watt KD6GGD PP-ASEL-IA ICBM: 121W 56' 57.8" / 37N 20' 14.9" > > Internet: steve @ Watt.COM Whois: SW32 > > Free time? There's no such thing. It just comes in varying prices... > > > > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" >
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