From owner-freebsd-arch@FreeBSD.ORG Mon Aug 18 19:52:13 2014 Return-Path: Delivered-To: arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 170E5A9A; Mon, 18 Aug 2014 19:52:13 +0000 (UTC) Received: from mail-ie0-x22d.google.com (mail-ie0-x22d.google.com [IPv6:2607:f8b0:4001:c03::22d]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id B02993F13; Mon, 18 Aug 2014 19:52:12 +0000 (UTC) Received: by mail-ie0-f173.google.com with SMTP id tr6so21213ieb.32 for ; Mon, 18 Aug 2014 12:52:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:reply-to:in-reply-to:references:date:message-id :subject:from:to:cc:content-type; bh=Qe9GhZoEMzzWfGPQC8PbPUvioN19l1P/k59IRCPkbQ8=; b=oDRBQqNL1uly0yKgisXzKunZWnAlbWynVWY0IxFP+h5fbXKgThmkLGC8EBoTeQvG4h Q8ZaGYkWWUg+4wvtP5EwQkEXY/JZSruoCTCOiseYqldqGtp9vMAVyER9qeBS6PvvRLAi qpm5bpXzRtuzLzLhh66wQl43fyUhrRBAvSgvBKRFMxY5gW4GU59Hz57v2k9LwxMm+RR4 zyILc/p91cxCATheQDxSsjFg9Y8DF0X2zrId0Mwl+qAVlFk9hY4EUp6UvN3Jw6GYqVRf DHynrairRSpAcKKa6iX91worxGstCyfWQo68jexA+Einhxl/O0ZixxpVcdpBljXBsomP WNGQ== MIME-Version: 1.0 X-Received: by 10.43.70.66 with SMTP id yf2mr19814257icb.36.1408391532138; Mon, 18 Aug 2014 12:52:12 -0700 (PDT) Received: by 10.43.17.196 with HTTP; Mon, 18 Aug 2014 12:52:12 -0700 (PDT) Reply-To: alc@freebsd.org In-Reply-To: References: <53F215A9.8010708@FreeBSD.org> <20140818183925.GP2737@kib.kiev.ua> Date: Mon, 18 Aug 2014 14:52:12 -0500 Message-ID: Subject: Re: superpages for UMA From: Alan Cox To: Adrian Chadd Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.18-1 Cc: Konstantin Belousov , "freebsd-arch@freebsd.org" , Gleb Smirnoff , "Alexander V. Chernikov" , "Andrey V. Elsukov" X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 18 Aug 2014 19:52:13 -0000 On Mon, Aug 18, 2014 at 2:45 PM, Adrian Chadd wrote: > Hi! > > I dug into this a little bit last year. I saw a lot of time spent just > walking TLBs for VM pages when doing a lot of VM page -> network > pushing. > > On the sandy bridge boxes with 1G page entries, the TLB only has 4 entries. > > The high area of memory isn't 1G aligned, so we don't use 1G pages for > all the stuff that's allocated initially. That includes, among other > things, all the VM memory that you need. > > The other thing that crept up was that we don't try to reserve memory > in any way - we'll just fragment stuff quickly from the pmap and > allocate where we can when we can. So there's currently no attempt to > allocate small kernel structures from the same underlying 1G page. > > For uma_small_alloc(), there is VM_FREEPOOL_DIRECT. However, this is still tuned for 2 MB pages. > That'd be an interesting experiment - allocating VM entries and other > small things like rtentry and mbuf UMA entries from one or two 1GB > regions of memory. It may make better use of the 1G (or 2M) TLB > entries and keep things hot. > > > > -a > _______________________________________________ > freebsd-arch@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-arch > To unsubscribe, send any mail to "freebsd-arch-unsubscribe@freebsd.org" >