Antw: RE: Massive ISR to DSR delay caused by free()
"Peter Graf" <[email protected]>
| Newsgroups | gmane.os.ecos.general |
|---|---|
| Message-ID | <529E088D0200007E0000ABE5@Groupware> |
Thanks Bernd, I already tried the latest dlmalloc.cxx earlier, but apparently the simple variable block implementation is used. Do you know in general, wether a DSR gets delayed if free() is called from a thread? Kind regards, Peter >>> Bernd Edlinger <[email protected]> schrieb am Dienstag, 3. Dezember 2013 um 14:37 in Nachricht <[email protected]>: > On Tue, 3 Dec 2013 11:19:17, Peter Graf wrote: >> >> Hi, >> >> under rare circumstances, we experienced a massive timing overflow of a > cyclical DSR. It turned out to be an issue with JFFS2, occurring after a > system reboot if long files had been written to the filesystem before. >> >> I found that the issue was only caused by JFFS2's >> >> malloc-ecos.c: jffs2_free_full_dnode() >> >> By using an oscilloscope, I could see that after the ISR was served, the DSR > was delayed, just because free() was called by jffs2_free_full_dnode(). More > precisely, the CPU time was spent in memalloc's >> >> mvarimpl.inl: Cyg_Mempool_Variable_Implementation::insert_free_block() >> >> At first I thought it was a locking issue within JFFS2. But in the end I > could not see any scheduler locks which might have caused it. >> >> I now have indications, that it could be a general issue with free(). A call > to free() from even a low priority thread seems to delay DSR execution after > the ISR! >> >> The allocator is compiled to be thread-safe, but in my opinion it would be a > major drawback if even a low priority thread could not call free() without > delaying a critical DSR. >> >> Can someone confirm this behaviour? Is it intended? >> >> Many thanks, >> Peter >> >> >> >> >> -- >> Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos >> and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss >> > > This sounds like a know deficiency of the very first Doug-Lee Malloc. > > Maybe you want check if this patch works for you? > > http://bugs.ecos.sourceware.org/show_bug.cgi?id=1001634 > > > Regards > Bernd Edlinger. > -- > Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos > and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss