On Monday 30 of August 2010 20:17:25 Luck, Tony wrote: > > I may tinker with this test a bit to include some short random > > amounts of hold-time for the lock, and delays between attempts > > to acquire it (to make it look more like a contended kernel lock > > and less like a continuous queue of processes trading around a > > lock that is never free > > I've been iterating ... adding new bits to try to reproduce the > kernel environment: Hi Tony, I've been also playing with my test case, and I haven't been able to reproduce it in user-space either. One thing I noticed was the apparently incorrect use of ALAT. The generated code for _spin_lock_irq contains: invala;; ld4.c.nc r11=[r32] // Other instructions not affecting r20 ld4.c.nc r20=[r32] IIUC, the subsequent compare can use an undefined value (r20 is not modified anywhere in this function, except by the ld4.c.nc, but that happens only on an ALAT miss, right?). I changed the corresponding code in __ticket_spin_lock to: asm volatile ("ld4.c.nc %0=[%1]" : "+r"(serve) : "r"(p) : "memory"); (NB the "+r" constraint instead of "=r") The generated code now re-uses r15. Unfortunately, Hedi's test case still fails for me. :( Petr Tesarik -- To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html