Re: mutexes, IPL, tty locking

2010-02-08 Thread David Holland
On Tue, Feb 09, 2010 at 12:20:48AM +, YAMAMOTO Takashi wrote: > > I'm not suggesting that we use this as such (and it would take quite a > > bit of work to merge it) but I think the general approach is worth > > considering. > > i don't think it's worth to do at this point because > - mu

Re: mutexes, IPL, tty locking

2010-02-08 Thread YAMAMOTO Takashi
hi, > On Thu, Oct 22, 2009 at 12:32:12PM +0100, Mindaugas Rasiukevicius wrote: > > IPL is only being raised and that works in reference counting principle. > > Therefore IPL is lowered (and only to IPL_NONE) after the last release, > > see ci_mtx_oldspl and ci_mtx_count. Which means that order

Re: mutexes, IPL, tty locking

2010-01-27 Thread David Holland
On Tue, Jan 26, 2010 at 10:39:23AM +, Andrew Doran wrote: > > I'm not sure it's as rare as all that; it just mostly doesn't overtly > > fail. Instead you end up silently running at a higher IPL than > > necessary, and that buys you longer interrupt latencies and more > > dropped packets and

Re: mutexes, IPL, tty locking

2010-01-26 Thread Andrew Doran
On Fri, Oct 30, 2009 at 07:43:24AM +, David Holland wrote: > On Thu, Oct 29, 2009 at 09:41:12PM +, Mindaugas Rasiukevicius wrote: > > David Holland wrote: > > > if (oldspl == highest && cur->l_iplcounts[highest-1] == 0) { > > > while (highest > 0 && cur->l_iplcounts[highest-1] == 0