From owner-freebsd-current@FreeBSD.ORG Thu May 29 20:05:51 2014 Return-Path: Delivered-To: freebsd-current@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 122B0C47; Thu, 29 May 2014 20:05:51 +0000 (UTC) Received: from mail-qg0-x233.google.com (mail-qg0-x233.google.com [IPv6:2607:f8b0:400d:c04::233]) (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 980412248; Thu, 29 May 2014 20:05:50 +0000 (UTC) Received: by mail-qg0-f51.google.com with SMTP id q107so2538157qgd.38 for ; Thu, 29 May 2014 13:05:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:date:message-id:subject:from:to:cc:content-type; bh=aQSK5AwvJmcQGU619gR/OZIpfv04X6HaIrb1kfCi5qw=; b=zsX/yxIEQvtasjl5hcweLSNKSO3ATrVdBlLO37fhHVPQ1TYQyxTNgtkFt0F3ccX5jn oPzyV0/R1BEnIQwj3ygExbtG11y8TypxOUnmwqFhPlKHGpiPv3YGLVJP/Am2o1b/mzvS AwS+TmBw61K4QaIbsjYp8QbS0SyN3l5ZhhjOU6kNgBO5BbQJcVfqCUlrEEo1AtRlHiVO uF8r2HR2JxXXElgNY5Q4hydpZCq22QTHu3Ax/r6gwN9D+koo3NmWfimSm9TfoJza7KxD fXbxQSo/oMdnHfVBGEdAxGjtjjCTWPRYZnvvZErQH/ZLq48k1S1bWqicQ+1xz2H4JjQm 5kwg== MIME-Version: 1.0 X-Received: by 10.224.16.199 with SMTP id p7mr14060418qaa.76.1401393949767; Thu, 29 May 2014 13:05:49 -0700 (PDT) Sender: adrian.chadd@gmail.com Received: by 10.224.191.201 with HTTP; Thu, 29 May 2014 13:05:49 -0700 (PDT) Date: Thu, 29 May 2014 13:05:49 -0700 X-Google-Sender-Auth: luKlKqZH9Kv-ske-xW216wOqaAs Message-ID: Subject: cpuid_t typedef? (was Re: Processor cores not properly detected/activated?) From: Adrian Chadd To: John Baldwin Content-Type: text/plain; charset=UTF-8 Cc: Attilio Rao , freebsd-current , Jia-Shiun Li , Alan Somers , Tim Bishop X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.18 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: Thu, 29 May 2014 20:05:51 -0000 On 29 May 2014 11:44, John Baldwin wrote: > On Thursday, May 29, 2014 2:24:45 pm Adrian Chadd wrote: >> On 29 May 2014 10:18, John Baldwin wrote: >> >> >> > It costs wired memory to increase it for the kernel. The userland set size >> >> > can be increased rather arbitrarily, so we don't need to make it but so large >> >> > as it is easy to bump later (even with a branch). >> >> >> >> Well, what about making the API/KBI use cpuset_t pointers for things >> >> rather than including it as a bitmask? Do you think there'd be a >> >> noticable performance overhead for the bits where it's indirecting >> >> through a pointer to get to the bitmask data? >> > >> > The wired memory is not due to cpuset_t. The wired memory usage is due to things >> > that do 'struct foo foo_bits[MAXCPU]'. The KBI issues I mentioned above are >> > 'struct rmlock' (so now you want any rmlock users to malloc space, or you >> > want rmlock_init() call malloc? (that seems like a bad idea)). The other one >> > is smp_rendezvous. Plus, it's not just a pointer, you really need a (pointer, >> > size_t) tuple similar to what cpuset_getaffinity(), etc. use. >> >> Why would calling malloc be a problem? Except for the initial setup of >> things, anything dynamically allocating structs with embedded things >> like rmlocks are already dynamically allocating them via malloc or >> uma. >> >> There's a larger fundamental problem with malloc, fragmentation and >> getting the required larger allocations for things. But even a 4096 >> CPU box would require a 512 byte malloc. That shouldn't be that hard >> to do. It'd just be from some memory that isn't close to the rest of >> the lock state. > > Other similar APIs like mtx_init() don't call malloc(), so it would be > unusual behavior. However, we have several other problems before we can > move beyond 256 anyway (like pf). Maybe behaviour has to change over time. :( anyway. Besides all of this - I'm thinking of just introducing: typedef uint32_t cpuid_t; .. then once we've converted all the users, we can make NOCPU something other than 255 (which is the other limiting factor here..) Any objections? -a