June 2003 - Darwin-kernel - lists.apple.com

Re: Socket NKE performance
by Justin C. Walker 05 Jun '03

05 Jun '03

On Thursday, June 5, 2003, at 07:33 AM, Stiphane Sudre wrote: I'm testing what kind of performance I can get from a Socket NKE communication from a Kernel Extension to a user land application. I set the recv_space of the socket to be 224 KB in the Kernel In the application, I'm using a CFSocket to read the data when available. To communicate with the application I'm sbappending 32 Bytes data using the same kind of code that the NKE tcpdumper sample code. My unrealistic dream is to reach a peak of 1 MB/s. But 300 KB/s would already be fair. >From the test I'm making, the performance can just reach 25 KB/s. Is this not a bit weak compared to what should be expected? Yup, it's quite low. If you are just in a loop, sbappending 32 bytes at a time, I don't know that you'll get high performance, and you will certainly churn up a lot of CPU cycles no matter what. What are you trying to achieve? Regards, Justin -- Justin C. Walker, Curmudgeon-At-Large * Institute for General Semantics | Men are from Earth. | Women are from Earth. | Deal with it. *--------------------------------------*-------------------------------* _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

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Socket NKE performance
by Stéphane Sudre 05 Jun '03

05 Jun '03

I'm testing what kind of performance I can get from a Socket NKE communication from a Kernel Extension to a user land application. I set the recv_space of the socket to be 224 KB in the Kernel In the application, I'm using a CFSocket to read the data when available. To communicate with the application I'm sbappending 32 Bytes data using the same kind of code that the NKE tcpdumper sample code. My unrealistic dream is to reach a peak of 1 MB/s. But 300 KB/s would already be fair. >From the test I'm making, the performance can just reach 25 KB/s. Is this not a bit weak compared to what should be expected? _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

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driver open
by Joseph Gabriel Echeverria 04 Jun '03

04 Jun '03

Is there a way to be notified everytime an I/OKit's open function is called? I want to have a KEXT which monitors the behavior of an I/O Kit driver. I can use the IOService::message() routine to get informed when the driver closes, but I can't find a message for when it is opened. Thanks, Joey Echeverria _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

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Re: Having problems with .gdbinit kernel macros...
by Quinn 04 Jun '03

04 Jun '03

At 9:56 -0700 1/6/03, Shawn Erickson wrote: On Sunday, June 1, 2003, at 01:56 AM, Quinn wrote: At 13:57 -0700 31/5/03, Shawn Erickson wrote: Or do I need to have a debug/symboled build of the kernel for them to work? You need to have kernel symbols for the kernel macros to work. A debug kernel is not required. So a symboled kernel or just the symbols (what their is in mach.sym)? AFAIK there are two sources of kernel symbols. 1. If you build the kernel yourself (using the instructions from "IMOSX:Kernel Programming"), the result is a "mach_kernel" file, which you install on the victim machine, and a "mach_kernel.sys" file, which is the kernel symbols which you load into GDB on the build machine using "add-symbol-file". 2. When Apple builds Mac OS X ourselves, we build and archive this file. Currently we do not have a formal process for distributing these symbol files, but we're working on it. S+E -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Technical Support * Networking, Communications, Hardware _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

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Re: Locking and synchronization primitives
by Wally Crooze 03 Jun '03

03 Jun '03

Brian Bergstrand wrote: Wally Crooze wrote: > A couple of more things on locking/synchronization primitives... > > How effective are the implementations of funnels and other locking > mechanisms (e.g. simple_locks) for SMP systems? I noticed that > simple_lock is defined as either 1 (as funnels are in effect), > disable_preemption (on Uni-processors) or usimple_lock (on SMP > systems). I was under the impression that usimple_locks were for > uni-processor systems... this is confusing. OS X is always in "SMP" mode, even on UNI machines. This is because the kernel is always compiled with pre-emption turned on. So simple locks will act the same as on SMP machines. I'm not sure I understand this statement. Pre-emption is a mechanism to allow multi-threading in a non-cooperative mode, I'm not sure how this effects multi-processors. I would hope that simple_locks and funnels enforce multi-processor safe locking. Are you saying that using the interface disable_preemption tells the other CPU to suspend their processing? Or is usimple_lock mechanism the correct interface to use? My problem is not simple. I am attempting to port a filesystem that uses many locking/synchronisation interfaces which aren't supported by darwin. I need interfaces which allow to check whether a lock is held and distinguish which thread is the owner. Also I need to be able to "try" to obtain a lock, which in the case that it returns if it can't immediately succeed, with a return value indicating this. In the case of an rwlock "try" upgrade (i.e. "read_to_write") it would return immediately, still retaining the read lock, if it couldn't obtain the write lock. On this note, I haven't found any interfaces which allow me to timeout when waiting, as "try" would have a timeout of 0. Any suggestions? Are these operations not supported for a reason? I also need the ability to retrieve the "value" of the semaphore. As part of this I would prefer not to write my own locking/synchronization primitives from scratch as many of them would require some "ml" coding. Can all of these be done through Wait Queues? Anything to prevent me from redoing everything from scratch and driving me insane would be greatly appreciated. Also, as my filesystem also communicates via BSD Sockets with other systems do I need to obtain the Network Funnel or is this done under the covers? > Also, can the locking and synchronization primitives be nested > safely? > > i.e. > simple_lock(lock1) > simple_lock(lock2) > simple_unlock(lock2) > simple_unlock(lock1) You can, but this kind of code can lead to deadlocks pretty easily. You have to be careful. Does the simple_lock mechanisms modify and restore the priority and interrupts correctly? > Does simple_locks disable interrupts, etc? I can't remember if that is done for you, I always disable them manually when needed. What interface does this for you? > Also what interface is equivalent to synch-variables... such as > sv_init, sv_rmproc? Can't help you there. Actually, a synch-variable is just a semaphore initialised to 0. > I'm also looking for a mechanism that will allow me to attempt to > upgrade (i.e. read to write) an mrlock, but if it can't get it > immediately it will return still holding the read (similar to the > try versions of the other locks). Have you looked at lock__bsd__ in <sys/lock.h>? It is based around simple locks and supports read->write upgrades (I think). It may do what you need. No, I haven't, I suspect that this is only supported in BSD. The problem is that since I will have multiple threads, sometimes holding the funnel and other times not, I need a consistent locking/synchronization method which will work for both circumstances. -- Wally Crooze +-------------------------------------------------------+ | ,-_|\ Wally Crooze <wallycrooze(a)pobox.com> | | / \ | | \_,-._/ | | v | +-------------------------------------------------------+ _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

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Re: Scanning devices from inside the kernel
by Sam Vaughan 01 Jun '03

01 Jun '03

Well after a string of kernel panics, I spotted the following comment above the declaration of IORegistryIterator::getNextObject(): "The entry returned is retained while the iterator is pointing at it (its the current entry), or recursing into it. The caller should not release it." So be sure to remove the call to service->release() if you try out this code! I am surprised to see that in the Darwin source there are examples of an object returned by an iterator being accessed after the iterator has been released. If the iterator only retains the object whilst it is pointing at it, surely the caller would need to retain the object before releasing the iterator? See IOPMPagingPlexus::setAggressiveness for an example. Sam On Friday, May 30, 2003, at 15:00 Australia/Melbourne, darwin-kernel-request(a)lists.apple.com wrote: OSDictionary* services = IOService::serviceMatching(kIOMediaClass); if (!services) return; OSIterator* iterator = IOService::getMatchingServices(services); if (!iterator) return; while (true) { IOService* service = OSDynamicCast(IOService, iterator->getNextObject()); if (!service) break; printf("name: %s\n", service->getName()); // service->release(); NO! - see IORegistryIterator::getNextObject() } iterator->release(); services->release(); _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

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Re: Having problems with .gdbinit kernel macros...
by Quinn 01 Jun '03

01 Jun '03

At 13:57 -0700 31/5/03, Shawn Erickson wrote: Or do I need to have a debug/symboled build of the kernel for them to work? You need to have kernel symbols for the kernel macros to work. A debug kernel is not required. S+E -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Technical Support * Networking, Communications, Hardware _______________________________________________ darwin-kernel mailing list | darwin-kernel(a)lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.

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