Date: Sun, 28 Jun 2009 18:41:49 -0500 From: Alan Cox <alc@cs.rice.edu> To: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> Cc: alc@freebsd.org, freebsd-hackers@freebsd.org Subject: Re: large pages (amd64) Message-ID: <4A47FFBD.3070900@cs.rice.edu> In-Reply-To: <alpine.BSF.2.00.0906290024540.37501@wojtek.tensor.gdynia.pl> References: <alpine.BSF.2.00.0906281933580.1809@wojtek.tensor.gdynia.pl> <ca3526250906281451g4441441bt3718d37dd848590a@mail.gmail.com> <alpine.BSF.2.00.0906290024540.37501@wojtek.tensor.gdynia.pl>
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Wojciech Puchar wrote: >> >> other question - tried enabling it on my i386 laptop (256 megs >> ram), always >> mappings==0, while promitions>demotions>0. >> >> >> The default starting address for executables on i386 is not aligned >> to a 2/4MB page boundary. Hence, "mappings" are much less likely to >> occur. >> >> >> certainly there are apps that could be put on big pages, gimp >> editing 40MB bitmap for >> example >> >> >> Regards, >> Alan >> >> >> > how can i check how much (or maybe - what processes) 2MB pages are > actually allocated? I'm afraid that you can't with great precision. For a given program execution, on an otherwise idle machine, you can only estimate the number by looking at the change in the quantity "promotions + mappings - demotions" before, during, and after the program execution. A program can call mincore(2) in order to determine if a virtual address is part of a 2 or 4MB virtual page. Alan
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