January 2008 - Darwin-kernel

Re: Leopard - No filesystem icon on desktop
by Quinn 15 Jan '08

15 Jan '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com S+E -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Relations, Developer Technical Support, Core OS/Hardware _______________________________________________ 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.… At 15:00 +0800 15/1/08, Nick Blievers wrote: However, no desktop icon is appearing. The Finder in 10.5 has a preference for whether to show server volumes on the desktop, and it defaults to /off/. Make sure Finder > Preferences > General > Connected Servers is checked. This email sent to site_archiver(a)lists.apple.com

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Leopard - No filesystem icon on desktop
by Nick Blievers 15 Jan '08

15 Jan '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com User-agent: Thunderbird 2.0.0.0 (Macintosh/20070326) Any ideas? But I am not sure where diskutil gets this information from. Thanks! Nick 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.… Our filesystem is mounting successfully, and even appears to be registered with diskarbitration: from sysylog: KernelEventAgent[33]: tid 00000000 type 'cxfs', mounted on '/mnt/foo', from '/dev/cxvm/foo' And then diskarb sends off a bunch of notifications: com.apple.diskarbitrationd[40]: created disk, id = /dev/cxvm/foo. com.apple.diskarbitrationd[40]: dispatched callback, id = 0000000000035B2C:000000000030CE10, kind = disk appeared, disk = /dev/cxvm/foo. cxfsmac6:~ nickb$ disktool -l ***Disk Appeared ('cxvm/foo',Mountpoint = '/mnt/foo', fsType = 'cxfs', volName = 'foo') <snip> However, no desktop icon is appearing. If I navigate to /mnt/foo in Finder, /mnt/foo has a network filesystem icon, however if I get info on /mnt/foo, it is says "Kind: Alias" with "Original: /mnt/foo" (ie the same path). Not sure if the Alias thing is related or not. I can't find any errors in syslog that seem relevant, and I am at a bit of a loss. We had disk icons in Tiger. One hint, is diskutil list is producing some strange entries: /dev/(null) #: TYPE NAME SIZE IDENTIFIER 0: (null) (null) *0.0 B (null) This email sent to site_archiver(a)lists.apple.com

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Re: G4
by Eric Long 14 Jan '08

14 Jan '08

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Re: G4
by Rick Macklem 14 Jan '08

14 Jan '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Mon, 14 Jan 2008, Hector Martinez wrote: rick _______________________________________________ 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.… Hello, Well i have problem in my hard disk , I don't can partion my disk, because my parents buy me this g4 mac have one partition my disk is the 80 GB, but I need parttion in 3 parts, so how I can doing? One way is to boot the install disk and then run "Disk Utility" from the "Utilities" pulldown menu you get after selecting a language. Unfortunately, you will have to re-install Mac OS X after doing the partitioning. I suspect there are ways which can avoid re-installing, but I don't know what they are (assuming the single drive is the system disk). This email sent to site_archiver(a)lists.apple.com

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G4
by Hector Martinez 14 Jan '08

14 Jan '08

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Re: Panic in OSMalloc??
by Michael Smith 11 Jan '08

11 Jan '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Jan 11, 2008, at 9:05 AM, Vishal Shetye wrote: = Mike _______________________________________________ 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.… Hi Mike, Thanks for your comments. Actually, I'm in bug-fixing phase and changes in the code would require thorough testing. I would be doing some changes as per suggestions in this thread. But still if you could clarify a few things - - Is there any specific reason that I see panic only on iMac(10.4.8) and not on MacPro(10.4.9) or MacMini(10.4.7)? Luck and variability in your test coverage caused by permutation of your test by characteristics of the various systems being tested. - what are the consequences of sleeping while holding a lock? Deadlock, or in some cases (e.g. the one you are hitting) a panic due to sanity-checking in the code. This email sent to site_archiver(a)lists.apple.com

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Re: Panic in OSMalloc??
by Michael Smith 11 Jan '08

11 Jan '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Jan 11, 2008, at 8:53 AM, Vishal Shetye wrote: Vishal, = Mike _______________________________________________ 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.… Hi, First of all thanks for your quick reply. What all you are saying is true but it is like our product is almost at release phase and I see panic only on iMac not on MacPro or Macmini and that too very infrequently. The bug you have described is fatal. It is unlikely to be the only one caused by a mis-understanding of what spinlocks are and how they work, and those others may well be fatal as well. I don't know about you, but I couldn't ship a product with a known bug like that in it in good conscience. This email sent to site_archiver(a)lists.apple.com

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RE: Panic in OSMalloc??
by Vishal Shetye 11 Jan '08

11 Jan '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:from:to:cc:references:subject:date:message-id:mime-version:content-type:content-transfer-encoding:x-mailer:in-reply-to:thread-index:x-mimeole; bh=MetaqInJoQ51s9N2CXBhkAR6LHR6j7i+FOJHN4f9u3c=; b=oH8F3r05rXXnsofz9pHyIhU7dF8ooadxgLNhWPVRBltKf9cYJedSycbEHVrcCMWf93NSfEQz9FCzwRXSYXAPElW58mfAUmmbvffM+uK7v//Wc7jn3u+IlZ3ecL9/kGdHAajCg8mr33FzA1M+yK3sjWjA7q76oUh/tNsVc4I5VsM= Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:references:subject:date:message-id:mime-version:content-type:content-transfer-encoding:x-mailer:in-reply-to:thread-index:x-mimeole; b=l2lM+/Z6Y7Z2dYH2irQVMCpHC2zj+fuIKAyLCLzVD27Fp4StQ+E2XbLIy3Ykr0AjPu2EvUj0c3B7gfbQIznp6g51A0uOBbFLSRu16rAY5vifdv0lv8b86rK6ugFMEEhaxp74kk69kZkwcI1Sw2VUjlJp08HsJV9KgC/9xLcideE= Thread-index: AchUchEa4kw+5ok2SxSUkO4R10r0pwAACPkg Hi Mike, Thanks for your comments. Actually, I'm in bug-fixing phase and changes in the code would require thorough testing. I would be doing some changes as per suggestions in this thread. But still if you could clarify a few things - - Is there any specific reason that I see panic only on iMac(10.4.8) and not on MacPro(10.4.9) or MacMini(10.4.7)? - what are the consequences of sleeping while holding a lock? ________________________________ Thanks - vishal shetye -----Original Message----- From: Michael Smith [mailto:drivers@mu.org] Sent: Friday, January 11, 2008 10:20 PM To: Vishal Shetye Cc: darwin-kernel(a)lists.apple.com Subject: Re: Panic in OSMalloc?? On Jan 10, 2008, at 11:15 PM, Vishal Shetye wrote: > Could you please explain what are the consequences of calling > OSMalloc with > some spin lock held. > I'm using lck_spin_lock() to lock a global variable before OSMalloc > and > release it once the item allocated has been added to a queue. Why would you do this? Firstly - spinlocks are a low-level primitive; they are not generally suitable for use in high-level code. At the level you are working, you should almost never need a spinlock - use a proper mutex if you must, but strive whenever possible to design your code so that you don't need locking in the first place. Secondly; why are you locking the global and then blocking? You should be using a try/backout scheme to avoid holding the lock while you sleep: LOCK flag = condition UNLOCK if (flag) thing = allocate() LOCK if (!condition) do_free = true else do_free = false queue_enter(thing) endif UNLOCK if (do_free) free(thing) endif endif = Mike _______________________________________________ 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: malloc returning NULL, was Panic in OSMalloc??
by Michael Smith 11 Jan '08

11 Jan '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Jan 11, 2008, at 8:48 AM, Rick Macklem wrote: I just responded to the "Panic in OSMalloc??" thread and then realized that "what to do when malloc returns NULL" is an interesting question, for which I don't have a good answer... It seems to me that a non-blocking malloc returning NULL could just indicate that the allocator has hit a transient high water mark and retrying the allocation allowing blocking would make sense? There are a couple of notable exceptions: This leads to a couple of interesting consequences: = Mike _______________________________________________ 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.… When malloc returns NULL, it makes sense that the system is in some sense constipated. To know how much, you'd need to know how the allocators are implemented and what they are being used for. (Beyond what I know about MacOS X.) Whether or not retrying a blocking malloc when it returns NULL is a good plan is more questionable. It seems to me that, for this case, the system may be pretty badly constipated and returning ENOMEM may be preferable? My NFS code was written way back when, when the BSD kernel malloc never failed for the blocking case, so I didn't have to deal with this. I'm hoping others will have comments? rick This is actually a great topic. I have a deal of input, as I was one of the instigators of the original M_NOWAIT cleanup in FreeBSD, and we hashed this out fairly well at the time. At most points in the kernel when you're allocating memory, you're doing work for someone else. What you can do about failures largely depends on how that client is going to deal with a transient failure. Most ultimate clients are willing to block arbitrarily long, but are not prepared to deal with transient or retryable failures. In the common case, this means that you're better off waiting in malloc. You should not be trying to second-guess the state of the system; you should be counting on the system to do something sensible and servicing your client according to their expectations. - You may be in a state where you cannot block. Typically, I'd say that if you need to allocate but you can't block, you need to go back and fix your design because it's busted, but there are always exceptions. To make this work, you have to have a fallback strategy that isn't going to upset your client. - It is sometimes the case that if you can make an allocation on the nonblocking path you can achieve an optimisation and avoid invoking a slower path to do the work. - You may be holding a lot of memory already. If you're in a state where you believe that you may be contributing to or causing kernel map starvation, you might want to implement your allocations in a more tentative fashion. This really still falls into the "busted" category; if you know you're likely to be starving the kernel out, you should redesign rather than mitigate, but again there are always exceptions. In this case, your best bet is likely to be to backoff and retry. - The system needs to have strategies in place for making forward progress when normal allocations are failing/blocking. - Subsystems that use allocated memory may be better off requiring that their clients do the allocation according to their constraints, rather than trying to offer blocking/nonblocking versions of their interfaces. This email sent to site_archiver(a)lists.apple.com

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RE: Panic in OSMalloc??
by Vishal Shetye 11 Jan '08

11 Jan '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:from:to:cc:references:subject:date:message-id:mime-version:content-type:content-transfer-encoding:x-mailer:in-reply-to:thread-index:x-mimeole; bh=toaJuE5rYKn6MWfPpE3DkmjM1iZTV9fO/aBIaiow/sg=; b=WvuBYDRb2G6wH12SjkiBAknpveiLPtBli39XdMvt8msaAZTr2xavStQQJp8TnfgLXH1xzvZ+iMGa9XdGF879yqymrZ1cl/XF6n0wd+gKFylCRKq5T33CFSSoPKE/yYt/ZOoNcKiYth937ta5GLRGm43VSSPAd/G0Atytz0FnE8Q= Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:references:subject:date:message-id:mime-version:content-type:content-transfer-encoding:x-mailer:in-reply-to:thread-index:x-mimeole; b=ubBv+F9j+ZADvVMG1lzYM16oDnfbr8zwLoZnUgveYv+Z3U0AwWwvZRPtGdJS665CuNrzDhMdUpHcJZaX68jAeGX+90O4PDks4gk9gB/gfKuFon9Bxa0zQlazvUdyL6ubZr/pI6I9iNBr6AhzaHG8mkf+Os+/pnnpSYI7l3DczNk= Thread-index: AchUaxPFxexhXqGTQOeYhuOaQP82AgABuJRA Hi, First of all thanks for your quick reply. What all you are saying is true but it is like our product is almost at release phase and I see panic only on iMac not on MacPro or Macmini and that too very infrequently. So thanks for suggestion, may be I should consider this change. ________________________________ thanks - vishal shetye -----Original Message----- From: Rick Macklem [mailto:rmacklem@uoguelph.ca] Sent: Friday, January 11, 2008 9:33 PM To: Vishal Shetye Cc: darwin-kernel(a)lists.apple.com Subject: RE: Panic in OSMalloc?? On Fri, 11 Jan 2008, Vishal Shetye wrote: > Hi Brian, > Could you please explain what are the consequences of calling OSMalloc with > some spin lock held. > I'm using lck_spin_lock() to lock a global variable before OSMalloc and > release it once the item allocated has been added to a queue. I'm not Brian and won't pretend to be, but... the short version is that you can't block holding a spin lock, as I understand it. (Since any other thread would just be busy waiting in a tight loop waiting for the lock while the thread holding the lock blocked, it wouldn't make much sense, even if the implementation permitted it.) > > Besides returned NULL value, is there any other difference between > OSMalloc() and OSMalloc_noblock()? > > In case OSMalloc_noblock() returns NULL can I try allocation immediately? Probably not a good plan. I'd guess that it will keep returning NULL until some other thread frees up some memory. Since looping on OSMalloc_noblock() would not block, it would hog the CPU. (In a traditional non-preemptive BSD kernel, the system would be hung, but I don't know diddly about the Mach side of things, so I don't know if other Mach threads would still be able to run and eventually release memory.) (Hopefully others with more expertice on the Mach side will chime in.) How I handle these situations (not saying it's the right way, but it is an easy way:-) is: - malloc new structure, blocking as required, until I have one - lock - search list and add new one, as required - unlock - free new one, if it wasn't needed (Yep, this case results in an extraneous malloc/free.) Another easy way (not so easy if multiple lists and structures are involved): tryagain: - lock - search list - if new one needed - if no new one allocated - attempt non-blocking allocation - if new one is allocated - add to list - else - unlock - do blocking allocation of new one - goto tryagain - add to list - unlock - if new one allocated, but not used - free new one Others will probably have more clever approaches. Personally, I'm a big KISS (keep it simple stupid) proponent, unless it is a critical path w.r.t performance. Have fun with it, rick _______________________________________________ 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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