Date: Fri, 16 May 1997 11:48:54 +0300 (EEST) From: Narvi <narvi@haldjas.folklore.ee> To: Terry Lambert <terry@lambert.org> Cc: James Mansion <james@westongold.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: mmap() Message-ID: <Pine.BSF.3.96.970516114759.6813F-100000@haldjas.folklore.ee> In-Reply-To: <Pine.BSF.3.96.970516110353.6813E-100000@haldjas.folklore.ee>
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On Fri, 16 May 1997, Narvi wrote: > > > On Thu, 15 May 1997, Terry Lambert wrote: > > > > > It would have a cost higher than not doing it (ie: non-zero). Using > > mmap() and then doing sequential I/O is probably a very limited market, > > so John would have to amke a decision to accept the non-0 degradation > > on that basis. > > > > Well, isn't grep doing the same? Mmap a file and then walk it line by line > and output the line matching the regular expression? Any program that > processes some kind of text file line by line will most probably express > the same kind of access pattern. > > I am not sure, but in case of several processes accessing one file using > MADV_WILLNEED / MADV_DONTNEED could perhaps help? > > Sander > > By the way - in the source of grep, madvise(.. MADV_SEQUENCIAL ..) is > commented for being slover. I will give it a try... > Well, FreeBSD grep doesn't use mmap, as HAVE_WORKING_MMAP is not defined in the Makefile... Sander > [a huge snip] > > > > > Regards, > > Terry Lambert > > terry@lambert.org > > --- > > Any opinions in this posting are my own and not those of my present > > or previous employers. > > > >
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