Hi Paul, Am 07.11.24 um 18:51 schrieb Paul Boddie:
Hello,I thought I might as well ask this since the mailing list has been somewhat active recently. I have been testing some of my software, but after a certain period of time, I experience errors of the following form: l4re_kernel: ERROR: more-mem(1000): Cannot provide more memory. l4re_kernel: ERROR: mmap() called: unimplemented! size=100000 As far as I can tell, uclibc_morecore and mmap in... pkg/l4re-core/l4re_kernel/server/src/mem.cc ...are respectively responsible for these errors, the former being called by __malloc_trim, itself called by free in... pkg/l4re-core/uclibc/lib/contrib/uclibc/libc/stdlib/malloc-standard/free.c Looking at the uclibc_morecore implementation, it seems that the "program break" is defined only once, with a dataspace of 64 pages being allocated, and any subsequent sbrk call will not cause this allocated space to be extended further. Have I understood this situation correctly?
Yes. The l4re_kernel has a static 64K heap for its own allocations. So far this has been enough and when it is exhausted, it's usually a sign of something going wrong somewhere else.
As always, I assume that I am making some kind of mistake, in this case probably not deallocating memory when I should be and thus exhausting theavailable space.
How long is your application running? Is it doing a lot of (small) allocations and deallocations? The l4re_kernel maintains the memory map for your application. For each entry in this map memory from the heap is used. So in case of a lot of small allocations this map grows and might use all of the heap. However, I would also expect a visible slowdown in your application on each memory de/allocation. Are you seeing any of this?
Are there any convenient ways of monitoring memory allocation in L4Re?
From the top of my head: Try the `l4re_dbg` flags: Add `l4re_dbg = 0xff` to your application startup in ned as parameter next to the caps table.
example: https://github.com/kernkonzept/mk/blob/master/conf/examples/x86-fb.cfg#L25You can also trigger a `debug_dump` of the l4re_kernel's memory map via the Debug_obj::debug() function. I'd try `cap_cast`ing the `L4Re::Env::env()->rm()`/l4re_kernel cap to `L4Re::Debug_obj` and the call the `debug()` function. The `function` parameter is unused in the l4re_kernel (l4re-core/l4re_kernel/server/src/region.cc), so zero or a dummy function should be ok.
So it is a way, if it's a convenient one? Well, .. ;-) Cheers, Philipp -- [email protected] - Tel. 0351-41 883 221 http://www.kernkonzept.com Kernkonzept GmbH. Sitz: Dresden. Amtsgericht Dresden, HRB 31129. Geschäftsführer: Dr.-Ing. Michael Hohmuth
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