Date: Thu, 23 Sep 1999 02:35:19 -0700 (PDT) From: Alfred Perlstein <bright@wintelcom.net> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: Kevin Day <toasty@dragondata.com>, "Daniel C. Sobral" <dcs@newsguy.com>, hackers@FreeBSD.ORG Subject: Re: Idea: disposable memory Message-ID: <Pine.BSF.4.05.9909230233570.6368-100000@fw.wintelcom.net> In-Reply-To: <199909230904.CAA23644@apollo.backplane.com>
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On Thu, 23 Sep 1999, Matthew Dillon wrote: > > :> > Thoughts? > :> > :> man madvise? > :> > : > :Yeah, but MADV_FREE doesn't really do what I need. I have no idea if the > :system actually did free my ram or not. I want to hang on to the data, but > :if more ram is needed, then it can be discarded, but I need to know that it > :did, so that I can recreate it. Checking every time I blit an object to see > :if the page is zero'ed won't work. > : > :Kevin > > madvise ... MADV_DONTNEED is what you want. The data will remain mapped > until the system reuses it, at which point it reverts to zero-fill. Don't you mean MADV_FREE? -Alfred > > The system will reuse the data fairly quickly, even if the system is > not all that loaded. > > You can lock the page back in simply by writing to something in the page. > > The system implements this madvise feature by marking the pages clean. > If you happen to write to the page before the system reuses it, it of > course gets redirtied. If you don't and the system reuses the page, > it goes bye bye (turns into zero-fill) from the point of view of your > process. > > -Matt > Matthew Dillon > <dillon@backplane.com> > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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