Date: Fri, 20 Sep 2013 15:20:35 +0000 From: Sebastian Kuzminsky <S.Kuzminsky@F5.com> To: Patrick Dung <patrick_dkt@yahoo.com.hk> Cc: Sebastian Kuzminsky <S.Kuzminsky@F5.com>, "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>, "ivoras@freebsd.org" <ivoras@freebsd.org> Subject: Re: About Transparent Superpages and Non-transparent superapges Message-ID: <B3A1DB16-7919-4BFA-893C-5E8502F16C17@f5.com> In-Reply-To: <1379649991.82562.YahooMailNeo@web193502.mail.sg3.yahoo.com> References: <mailman.2681.1379448875.363.freebsd-hackers@freebsd.org> <1379520488.49964.YahooMailNeo@web193502.mail.sg3.yahoo.com> <22E7E628-E997-4B64-B229-92E425D85084@f5.com> <1379649991.82562.YahooMailNeo@web193502.mail.sg3.yahoo.com>
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On Sep 19, 2013, at 22:06 , Patrick Dung wrote: > >We at Line Rate (now F5) are developing support for 1 Gig superpages on = amd64. We're basing our work on 9.1.0 for now. > > > >An early preview is available here: > > > >https://github.com/Seb-LineRate/freebsd/tree/freebsd-9.1.0-1gig-pages-NO= T-READY-2 >=20 > That is cool. >=20 > What type of applications can take advantage of the 1Gb page size? > And is it transparent? Or applications need to be modified? It's transparent for the kernel: all of UMA and kmem_malloc()/kmem_free() i= s backed by 1 gig superpages. It's not transparent for userspace: applications need to pass a new flag to= mmap() to get 1 gig pages. This is useful in applications with high memory pressure, where memory band= width and TLB misses are a limiting factor. --=20 Sebastian Kuzminsky
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