From owner-freebsd-current@FreeBSD.ORG Mon Oct 18 13:40:40 2010 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 7C670106566B; Mon, 18 Oct 2010 13:40:40 +0000 (UTC) (envelope-from giovanni.trematerra@gmail.com) Received: from mail-ww0-f50.google.com (mail-ww0-f50.google.com [74.125.82.50]) by mx1.freebsd.org (Postfix) with ESMTP id 6A2708FC28; Mon, 18 Oct 2010 13:40:39 +0000 (UTC) Received: by wwb13 with SMTP id 13so318184wwb.31 for ; Mon, 18 Oct 2010 06:40:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:sender:received :in-reply-to:references:date:x-google-sender-auth:message-id:subject :from:to:cc:content-type:content-transfer-encoding; bh=jlhIjpPhIheME1iQ94xo08F1IIs55qBF/rMyxW0puPk=; b=mzFdhqSJXNRJTFx6BNt29qEIv6uFeimZCbwfstkI92buggVV8YcXafw9s3v31EwiOF gtl7+RxiQhvQnR9wox7JR1VYY8brLYLmiGfaL4D49CeHGC9ipj6FGYNbT37fOhc+sWY/ 125GaeUzuoB4aWg4fAmAedcHXFrH1J5gLd5uQ= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=pmv+IvnOZ7/yHylYYqAHpQwCYMihdd0/07npLDTBTQ05X9H5m2EyInATOYf0aOeRJw PBbkQKUPZZIwn/k/IDjEe2wyIfEfsXJ8OVs4ly4bXa2HESMwwoCfJybFHoEdHOcnHKE2 KKJadt8Q5MjwO/zBWMoB8BIJZcG5CjcuvcpmE= MIME-Version: 1.0 Received: by 10.227.128.7 with SMTP id i7mr877857wbs.165.1287409238045; Mon, 18 Oct 2010 06:40:38 -0700 (PDT) Sender: giovanni.trematerra@gmail.com Received: by 10.227.144.203 with HTTP; Mon, 18 Oct 2010 06:40:37 -0700 (PDT) In-Reply-To: <4CBBEBDF.3060905@freebsd.org> References: <4C9B9B9C.6000807@freebsd.org> <4CBBEBDF.3060905@freebsd.org> Date: Mon, 18 Oct 2010 15:40:37 +0200 X-Google-Sender-Auth: S-myIx_JcK8dZdmOJH3MTfvUgmk Message-ID: From: Giovanni Trematerra To: Andriy Gapon Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: alc@freebsd.org, freebsd-current@freebsd.org Subject: Re: panic in uma_startup for many-core amd64 system X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 18 Oct 2010 13:40:40 -0000 On Mon, Oct 18, 2010 at 8:40 AM, Andriy Gapon wrote: > on 23/09/2010 21:25 Andriy Gapon said the following: >> >> Jeff, >> >> just for the kicks I tried to emulate a machine with 64 logical CPUs usi= ng >> qemu-devel port: >> qemu-system-x86_64 -smp sockets=3D4,cores=3D8,threads=3D2 ... >> >> It seems that FreeBSD agreed to recognize only first 32 CPUs, but it pan= iced anyway. >> >> Here's a backtrace: >> #34 0xffffffff804fe7f5 in zone_alloc_item (zone=3D0xffffffff80be1554, >> udata=3D0xffffffff80be1550, flags=3D1924) at /usr/src/sys/vm/uma_core.c:= 2506 >> #35 0xffffffff804ff35d in hash_alloc (hash=3D0xffffff001ffdb030) at >> /usr/src/sys/vm/uma_core.c:483 >> #36 0xffffffff804ff642 in keg_ctor (mem=3DVariable "mem" is not availabl= e. >> ) at /usr/src/sys/vm/uma_core.c:1396 >> #37 0xffffffff804fe91b in zone_alloc_item (zone=3D0xffffffff80a1f300, >> udata=3D0xffffffff80be1b60, flags=3D2) at /usr/src/sys/vm/uma_core.c:254= 4 >> #38 0xffffffff804ff92e in zone_ctor (mem=3DVariable "mem" is not availab= le. >> ) at /usr/src/sys/vm/uma_core.c:1832 >> #39 0xffffffff804ffca4 in uma_startup (bootmem=3D0xffffff001ffac000, boo= t_pages=3D48) >> at /usr/src/sys/vm/uma_core.c:1741 >> #40 0xffffffff80514822 in vm_page_startup (vaddr=3D18446744071576817664)= at >> /usr/src/sys/vm/vm_page.c:360 >> #41 0xffffffff805060c5 in vm_mem_init (dummy=3DVariable "dummy" is not a= vailable. >> ) at /usr/src/sys/vm/vm_init.c:118 >> #42 0xffffffff803258b9 in mi_startup () at /usr/src/sys/kern/init_main.c= :253 >> #43 0xffffffff8017177c in btext () at /usr/src/sys/amd64/amd64/locore.S:= 81 >> [[[ >> Note: >> 1. Frame numbers are high because the backtrace is obtained via gdb remo= tely >> connected to qemu and also there is bunch of extra frames from DDB, etc. >> 2. Line numbers in uma_core. won't match those in FreeBSD tree, because = I've doing >> some unrelated hacking in the file. >> ]]] >> >> The problem seems to be with creation of "UMA Zones" zone and keg. >> Because of the large number of processors, size argument in the followin= g snippet >> is set to a value of 4480: >> >> args.name =3D "UMA Zones"; >> args.size =3D sizeof(struct uma_zone) + >> =A0 =A0 (sizeof(struct uma_cache) * (mp_maxid + 1)); >> >> Because of this, keg_ctor() calls keg_large_init(): >> >> else if ((keg->uk_size+UMA_FRITM_SZ) > >> =A0 =A0 (UMA_SLAB_SIZE - sizeof(struct uma_slab))) >> =A0 =A0 =A0 =A0 keg_large_init(keg); >> else >> =A0 =A0 =A0 =A0 keg_small_init(keg); >> >> keg_large_init sets UMA_ZONE_OFFPAGE and UMA_ZONE_HASH flags for this ke= g. >> This leads to hash_alloc() being invoked from keg_ctor(): >> >> if (keg->uk_flags & UMA_ZONE_HASH) >> =A0 =A0 =A0 =A0 hash_alloc(&keg->uk_hash); >> >> But the problem is that "UMA Hash" zone is not created yet and thus the = call leads >> to the panic. =A0"UMA Hash" zone is the last of system zones created. >> >> Not sure what the proper fix here could/should be. >> Would it work to simply not set UMA_ZONE_HASH flag when UMA_ZFLAG_INTERN= AL is set? >> >> >> And some final calculations. >> On the test system sizeof(struct uma_cache) is 128 bytes and (mp_maxid += 1) is 32, >> so it's already UMA_SLAB_SIZE =3D PAGE_SIZE =3D 4096. >> > > Here is a simple solution that seems to work: > http://people.freebsd.org/~avg/uma-many-cpus.diff > Not sure if it's the best we can do. > I don't know if it makes sense I only want to raise a flag. Is it safe to call kmem_malloc() before bucket_init() during uma_startup() to reserve room for CPU caches? Reading the top uma_int.h comment, it seems that the best way to handle this issue would be to implement and allow for dynamic slab sizes. I'm also afraid that memory footprint will be larger than now. -- Trematerra Giovanni