Paul Menage wrote: > On 11/23/06, Pavel Emelianov <[EMAIL PROTECTED]> wrote: >> Paul Menage wrote: >> > On 11/23/06, Pavel Emelianov <[EMAIL PROTECTED]> wrote: >> >> You mean moving is like this: >> >> >> >> old_bc = task->real_bc; >> >> task->real_bc = new_bc; >> >> cmpxchg(&tsk->exec_bc, old_bc, new_bc); >> >> >> >> ? Then this won't work: >> >> >> >> Initialisation: >> >> current->exec_bc = init_bc; >> >> current->real_bc = init_bc; >> >> ... >> >> IRQ: >> >> current->exec_bc = init_bc; >> >> ... >> >> old_bc = tsk->real_bc; /* init_bc */ >> >> tsk->real_bc = bc1; >> >> cx(tsk->exec_bc, init_bc, bc1); /* ok */ >> >> ... >> >> Here at the middle of an interrupt >> >> we have bc1 set as exec_bc on task >> >> which IS wrong! >> > >> > You could get round that by having a separate "irq_bc" that's never >> > valid for a task not in an interrupt. >> >> No no no. This is not what is needed. You see, we do have to >> set exec_bc as temporary (and atomic) context. Having temporary >> context is 1. flexible 2. needed by beancounters' network accountig. > > I don't see why having an irq_bc wouldn't solve this. At the start of > the interrupt handler, set current->exec_bc to &irq_bc; at the end set > it to current->real_bc; use the cmpxchg() that I suggested to ensure > that you never update task->exec_bc from another task if it's not > equal to task->real_bc; use RCU to ensure that a beancounter is never > freed while someone might be accessing it.
Oh, I see. I just didn't get your idea. This will work, but 1. we separate interrupt accounting from all the others' 2. for interrupts only. In case we want to set init_bc as temporary context all will be broken... We need some generic solution independent from what exactly is set as temporary exec_bc. >> >> Maybe we can make smth similar to wait_task_inactive and change >> it's beancounter before unlocking the runqueue? > > That could work too. Could work, but whether everyone will like such intrusion... I agree that stop_machine isn't nicer. This is a temporary solution that works for sure. Better one will follow... ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ ckrm-tech mailing list https://lists.sourceforge.net/lists/listinfo/ckrm-tech
