Date: Sat, 9 Jun 2012 10:59:28 +0100 From: "Robert N. M. Watson" <rwatson@freebsd.org> To: Mikolaj Golub <trociny@freebsd.org> Cc: Konstantin Belousov <kostikbel@gmail.com>, Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>, Alan Cox <alc@freebsd.org>, Ivan Voras <ivoras@freebsd.org>, freebsd-hackers@freebsd.org Subject: Re: SuperPages utilization survey Message-ID: <43D7AF1B-9BDB-4417-AF34-E75FB203A2B2@freebsd.org> In-Reply-To: <86k3zglsvm.fsf@kopusha.home.net> References: <jqac8f$6mn$1@dough.gmane.org> <alpine.BSF.2.00.1206011429160.20357@wojtek.tensor.gdynia.pl> <CAF-QHFXsi3SaF-rmFK-qM89LfnStKwRWN1-HRM4yg4Bt_SFAOg@mail.gmail.com> <86sje5kkl6.fsf@kopusha.home.net> <20120609083822.GJ85127@deviant.kiev.zoral.com.ua> <86obosluvk.fsf@kopusha.home.net> <20120609090740.GL85127@deviant.kiev.zoral.com.ua> <86k3zglsvm.fsf@kopusha.home.net>
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On 9 Jun 2012, at 10:46, Mikolaj Golub wrote: > On Sat, 9 Jun 2012 12:07:40 +0300 Konstantin Belousov wrote: >=20 > KB> Well, if I see a report informing me that some 2M region contains = 512 super > KB> pages, how should I interpret it ? For me, it is only one = superpage (mapping) > KB> that can be created in one 2M region. >=20 > Well, if I see a report like below: >=20 > PID START END PRT RES PRES SUP REF = SHD FL TP PATH > 48568 0x800c00000 0x820c00000 rw- 131072 0 51712 2 = 0 --S df=20 >=20 > it tells me that for the region 0x800c00000-0x820c00000 (512Mb) we = have 131072 > * 4k =3D 512Mb resident and 51712 * 4k =3D 202Mb (a litle less than a = half of the > region) promoted (mapped) to superpages. >=20 > If I had number of superpages here I would need additional knowledge = (a > superpage size) to calculate how effectively superpages are used. >=20 > But actually, no much difference for me. To get a number of superpages = is it > enough just to divide the result obtained counting normal-sized pages = by > (2M/4k) factor? Remember also that superpage sizes are not necessarily 2M on all = architectures, and in principle, many different page sizes might be = simultaneously supported (e.g., on MIPS). I wonder if there's some way = to capture that notion in the output somewhere so that, if we start = supporting more granular page size control (something Alan might comment = on), tool output doesn't need to be changed. Robert
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