October 2008 - Darwin-kernel

Re: which processor is a thread executing on?
by mm w 02 Oct '08

02 Oct '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:cc:in-reply-to:mime-version:content-type :content-transfer-encoding:content-disposition:references; bh=K9oYlzTw80pwj2iIET4nQpSuj5XihUvSRdwACb3u4Nc=; b=be+JWJmVZROvffSEyFSVfSdpPsxjWMMxUjjaNohljCPz+/J7Bfr0hq6M1km7FvVn7G G/aCm7zfkcX38OEx5FlrlWSbGBJTZrKHkn1Rb4MQSetQ1duicN0doeXUA5otlRsxmeqq 4sQJ3i/T+Mu4/qnR1VgSd+LovKzsYOzPddeZw= Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=mxIFAtOX/tioGmba8PY4AO/zzZqgET9A9Bji9WY9MYQxfP5T0qINifA2oSwM/AuWpQ GAaJiruNVo3sCU36gW1dgRmm0gizeUd1fIHLLVXk+6+cEEcF0DyGRPwfCmPLH5OeZb3k DsuX19X76o8tG2hFRcSFfIDT45qjzRC7FjFqg= There is no such thing regarding the fb kernel for the same reasons aka terry's answer anyway it could have a guardian to handle the case of a cpu-off/bind As I said beside of any technical challenge this is a choice _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: which processor is a thread executing on?
by Michael Crawford 02 Oct '08

02 Oct '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:in-reply-to:mime-version:content-type :content-transfer-encoding:content-disposition:references; bh=MWZHGgDnjXtTLmjScX2+HFfXUvJkEIOvQgRL3a38UfY=; b=n8ZZBsOsK99IX2k0/SnloVOhBsNefLpA1uSfvEAUYb/uSd5A7O2ArvC3z38gWBVWRC IuR3MYmBkwE1RvGWyOzyPBOEqsoID2pgi72vwSCCTu/tt2QwTLF5JmDQr8HCVFHFsAoM kLdG4awPlaSst+OlaRb/Ai14JoBwdKOp9XlI0= Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=W10aMTfbkJkQm/lc53lt8VRctzhMONJAcm2QRSTgnA6WVWsOEf4TbZ1MlUAADJ3AE9 wtxluqNunf6c4hYOHrI31ZYQykaZTmmv9+KDQRJlw27Kp3CabDyC9eZLriLBVCipvkSj cB5zJe9vaxWt9WI22jFuDFz41kRwAcQqhybMA= While there is almost certainly a better way to achieve your desired goal, you might find what you need in the Mach microkernel API. OS X' pthread implementation is a wrapper around Mach tasks. While the OS X kernel *is* built on top of Mach, Mach isn't in this case a microkernel - it's statically linked to the rest of the kernel, so as to avoid the context switching overhead that plagues true microkernels. It's just used to provide useful operating system primitives. The xnu kernel is the FreeBSD kernel on top of Mach, with a unique driver architecture called the I/O Kit. Mike -- Michael David Crawford mdcrawford at gmail dot com Enjoy my art, photography, music and writing at http://www.geometricvisions.com/ --- Free Compact Disc --- _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: which processor is a thread executing on?
by Terry Lambert 02 Oct '08

02 Oct '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com -- Terry _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… On Oct 1, 2008, at 5:10 PM, Nick Brandaleone <nbrand(a)mac.com> wrote: I am writing a multi-threaded app, and I would like to know which processor the thread is executing on. Is there a pthread function call to determine this? Dtrace will tell you which processor something is running on at the time you hit a trace point. You can get the same information via XRay instruments, and Shark traces can also be used to get it. A program thread itself can not ask. In part this is because the asking would require a system call, and that would only tell you the CPU that the system call happened on. In part it's because power management takes CPUs offline and online all the time, as needed; this is the same reason we do not permit binding threads to particular CPUs: it would not do you much good to bind a thread to a CPU that was subsequently powered down. This email sent to site_archiver(a)lists.apple.com

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Re: Hard links to directories
by Kevin Van Vechten 02 Oct '08

02 Oct '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com - Kevin On Oct 1, 2008, at 7:25 PM, Chris Idou wrote: OS-X 10.5 now allows you to hard link directories. _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… Directory hard links are really an implementation detail of Time Machine. It's not encouraged to create them (they're never created on non-Time Machine volumes), and it's not possible to create them except as root. I took a quick glance at getattrlist(2) and didn't see this value exported, so I'm guessing it's not (easily) available. However the link count of the directory seems to behave in the conventional unix way. i.e. it is the number of directories contained in that directory + 2 for "." and "..". Is there a way to find out the link count for directories, or to otherwise discover if a particular directory has hard links? This email sent to site_archiver(a)lists.apple.com

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Re: which processor is a thread executing on?
by mm w 02 Oct '08

02 Oct '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:in-reply-to:mime-version:content-type :content-transfer-encoding:content-disposition:references; bh=R9Vo4HWbKfeBGTe/0Rhd7ORX3wvjJER1qYaLXbYVIkM=; b=HtnLXM4lLo1YN6GVWtXJK4f7n2WuiOgfoU2L+gVAMSE1L2pMY09Lcp8SHntlzMNVU7 0JTeSQZotskxXEYmeczTe2DnEInKFP8Lq4J2S0YJsGd+B9Qy+zFH0GTlSsMdJhQGBU+H 41EPxEvXkdT5bxJd+8b9l7jnT4OK3+JyT7xl8= Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=rvQosj6lQF+PWtdyvcd3meMKktdfX0KYs9u+7iZwgbhgIbt1XMoyU8O45nW7bQd6Cx plWwZvU5+ECeAbFQg6PbWfpX7BNxsR82xNPIGHoemjuMF7DuK+YAdNp9lAWbL8+uSmFf 4Ig3ycp6Cfsqcy1pcETWYbBTVW4OfSrAyTxe4= Hi Nick, Darwin pthread doesn't implement some kind of mechanism like pthread_processor_bind_np there are some APIs (to bind a thread to a processor) on DragonFly, I think this is a choice in an OS design, and the choice in Darwin design is not to give access to this informatios and let the system handling it for you but if you could be more specific, maybe there is another way to make your app working Cheers! _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: Hard links to directories
by Chris Idou 02 Oct '08

02 Oct '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type:Message-ID; b=HPYQw4SlLYfc21mkAcUEOx2dEscRIdOkoM/L8LMZ2YIJl0Flk2vpfF3w4zqGyTfLmnTie4bCgT1if6WOL2CffLhl/eUnofLvKpEnnPBa6h+P8BKV8Ajb0eHRD5iljis7sm1WaOSs014lp5gud8Zb/9E61W76ZQ2eTR1p4ESBFN0=; A couple more questions: 1) How do permissions work? I notice that the system seems to stop you doing dangerous things like hardlinking /System to somewhere, even as root, but its not clear why this case is different. 2) I notice that once a directory has been hardlinked, it is forever tainted in some fashion. If I hardlink a directory somewhere, then unlink the 2nd link, then the original directory can never be trashed in the Finder for example. Such an attempt will fail, even though it is apparently no different to any other directory. Can anyone enlighten me about this? --- On Wed, 10/1/08, Chris Idou <idou747(a)yahoo.com> wrote: > From: Chris Idou <idou747(a)yahoo.com> > Subject: Hard links to directories > To: darwin-kernel(a)lists.apple.com > Date: Wednesday, October 1, 2008, 7:25 PM > OS-X 10.5 now allows you to hard link directories. > > However the link count of the directory seems to behave in > the conventional unix way. i.e. it is the number of > directories contained in that directory + 2 for > "." and "..". > > Is there a way to find out the link count for directories, > or to otherwise discover if a particular directory has hard > links? > > > > > > > _______________________________________________ > Do not post admin requests to the list. They will be > ignored. > Darwin-kernel mailing list > (Darwin-kernel(a)lists.apple.com) > Help/Unsubscribe/Update your Subscription: > http://lists.apple.com/mailman/options/darwin-kernel/idou747%40yahoo.com > > This email sent to idou747(a)yahoo.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Hard links to directories
by Chris Idou 02 Oct '08

02 Oct '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:Date:From:Reply-To:Subject:To:MIME-Version:Content-Type:Message-ID; b=OWdchJ4ZvCf1BuU0uaqMnQWI57PWeVLAK0h5uljYgx232URkxTulgmCqZsgR33WLY52RnszJSss4d+1ZfR7K2MzHoXan5igNSIz08CcdMWefMJ/vAp9gOcUWFZPNNmsV3R4Y5uD+6eYpcLqHb8tULGTLFSbqdzkivY6glXOjMsU=; OS-X 10.5 now allows you to hard link directories. However the link count of the directory seems to behave in the conventional unix way. i.e. it is the number of directories contained in that directory + 2 for "." and "..". Is there a way to find out the link count for directories, or to otherwise discover if a particular directory has hard links? _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: which processor is a thread executing on?
by Wade Tregaskis 02 Oct '08

02 Oct '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Wade _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… I am writing a multi-threaded app, and I would like to know which processor the thread is executing on. Is there a pthread function call to determine this? There is not. As Andreas noted, you can't do this reliably without being forcefully bound to a particular CPU, in which case you already know, and which is strongly discouraged in any case. You can do it, though. You can execute CPUID and figure it out from there. But CPUID is a very expensive little instruction - it takes something like ~100ns to execute on today's machines, and has other side-effects - so you don't want to call it too often. But the most pertinent question, really, is why you want to do this? Either there's a better way to do whatever you're ultimately trying to do, or it's something that you should file an enhancement request for, if it's worth doing. This email sent to site_archiver(a)lists.apple.com

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Re: which processor is a thread executing on?
by Andreas Fink 02 Oct '08

02 Oct '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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which processor is a thread executing on?
by Nick Brandaleone 02 Oct '08

02 Oct '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Hello, Thanks, Nick _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… I am writing a multi-threaded app, and I would like to know which processor the thread is executing on. Is there a pthread function call to determine this? This email sent to site_archiver(a)lists.apple.com

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