April 2021 - discuss - mailman3.cels.anl.gov

modifying scheduler event frequency?
by Phil Carns 21 Apr '21

21 Apr '21

Hi all, Is there a clean way to change a scheduler's event frequency on the fly? Browsing the API, I see two possibilities: * set it when the scheduler is first created (using ABT_sched_basic_freq?) * set it dynamically by manipulating the ABT_sched_get_data() pointer, but this seems especially dangerous since the sched data struct definition isn't public (i.e. it could cause memory corruption if the internal struct def changed) For some context (in case there is a different way to go about this entirely), I'm trying to figure out how to get ABT_info_trigger_print_all_thread_stacks() to print information more quickly, which IIUC relies on getting the active schedulers to call get_events() sooner. I'm happy to add some explicit ABT_thread_yield() shortly after the ABT_info_trigger_print_all_thread_stacks() to at least get the calling ES to execute it's scheduler loop immediately, but I think that won't matter much if it doesn't trip the frequency counter when I do it. Without this (at least with the _wait scheduler and threads that are occasionally tied up in system calls) I think the stack dump is likely to trigger too late to display what I'm hoping to capture when I call it. The first example I tried appeared to essentially defer dump until shutdown. thanks! -Phil

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dumping stack information for running ULTs
by Phil Carns 16 Apr '21

16 Apr '21

Hi all, I followed Shintaro's suggestions from the previous list email thread and was able to get a stack dump routine that works as expected. For all pools under my control I can see stack information like this for each ULT, with stack unwinding: == pool (0x557d5b8c4580) == === ULT (0x7f47429590c1) === id : 0 ctx : 0x7f4742959120 p_ctx : 0x7f4742958fe0 p_link : (nil) stack : 0x7f47427590c0 stacksize : 2097152 #0 0x7f4744461760 in ythread_unwind_stack () <+16> (RSP = 0x7f4742959010) #1 0x7f474445e3dd in ABT_thread_yield () <+157> (RSP = 0x7f4742959020) #2 0x7f474447e255 in __margo_hg_progress_fn () <+645> (RSP = 0x7f4742959040) #3 0x7f474446381e in ABTD_ythread_func_wrapper () <+30> (RSP = 0x7f47429590b0) #4 0x7f47444639c1 in make_fcontext () <+33> (RSP = 0x7f47429590c0) 00007f47427590c0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 00007f47427590e0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 ... That only works for ULTs that are literally in the pool, though, I think. I don't believe that I am getting information for ULTs that are executing (and thus are not presently in a pool data structure). Is there any way to accomplish that? I tried to at least get the caller's own stack at least by doing something like this: ABT_thread_self(&self); ABT_info_print_thread_stack(outfile, self); That almost works, but I'm just getting the raw address information and not the translated stack unwinding: p_ctx : 0x7f4742758fb8 p_link : (nil) stack : 0x7f4742559000 stacksize : 2097152 00007f4742559000: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 00007f4742559020: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 ... For completeness it would be nice if the caller's stack were also human readable, and even better if I could somehow find stack information for ULTs executing on other ESs as well. For our use case we typically spawn many detached threads into a service pool, so we aren't tracking thread references. thanks, -Phil

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Announcing the release of Argobots 1.1
by Iwasaki, Shintaro 01 Apr '21

01 Apr '21

Dear Argobots Users and Developers, We are excited to announce that a new stable release of Argobots 1.1 is now available for download. Argobots 1.1 added numerous features such as tool interface, extended work-unit data access routines, improved affinity interface, and stack unwinding for debugging. Argobots 1.1 fixed several bugs and clarified the behavior of each API. Production environments are encouraged to upgrade to this release. All the changes from Argobots 1.0 are summarized here: https://www.argobots.org/changes/argobots_1_1/ Please find the tarball on our downloads page: https://www.argobots.org/downloads/ We thank all the Argobots users and developers for supporting us. Best Regards, The Argobots team =============================================================================== Changes in 1.1 =============================================================================== - Added a tool interface to support a profiler (see ABTX_prof) - Supported the stack unwinding feature - Implemented static initializers for ABT_mutex and ABT_cond - Improved work-unit-local storage support - Added several utility functions - Improved support for affinity settings via an environmental variable - Enhanced memory management of ULT stacks and descriptors - Used futex when external threads call Argobots synchronization operations - Revised the API specification - Added support for XLC, PGI, Solaris, and ARM HPC compilers - Supported Autoconf 2.70 - Fixed several bugs

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