On Fri 25-08-17 23:39:36, Pavel Machek wrote: > On Fri 2017-08-25 10:04:42, Michal Hocko wrote: > > On Fri 25-08-17 09:28:19, Pavel Machek wrote: > > > On Fri 2017-08-25 08:35:46, Michal Hocko wrote: > > > > On Wed 23-08-17 19:57:09, Pavel Machek wrote: > > [...] > > > > > Dunno. < 1msec probably is temporary, 1 hour probably is not. If it causes > > > > > problems, can you just #define GFP_TEMPORARY GFP_KERNEL ? Treewide replace, > > > > > and then starting again goes not look attractive to me. > > > > > > > > I do not think we want a highlevel GFP_TEMPORARY without any meaning. > > > > This just supports spreading the flag usage without a clear semantic > > > > and it will lead to even bigger mess. Once we can actually define what > > > > the flag means we can also add its users based on that new semantic. > > > > > > It has real meaning. > > > > Which is? > > "This allocation is temporary. It lasts milliseconds, not hours." And why would such a semantic make any sense what so ever? We certainly do not try to wait for a pinned memory for $TIMEOUT when somebody really needs a larger memory block and there is a temporary allocation standing in the way. We simply do not know that an object is a temporary one. > > > You can define more exact meaning, and then adjust the usage. But > > > there's no need to do treewide replacement... > > > > I have checked most of them and except for the initially added onces the > > large portion where added without a good reasons or even break an > > intuitive meaning by taking locks. > > I don't see it. kmalloc() itself takes locks. Of course everyone takes > locks. I don't think that's intuitive meaning. I was talking about users of the flag. I have seen some to take a lock right after they allocated GFP_TEMPORARY object. > > Seriously, if we need a short term semantic it should be clearly defined > > first. > > "milliseconds, not hours." > > > Is there any specific case why you think this patch is in a wrong > > direction? E.g. a measurable regression? > > Not playing that game. You should argue why it is improvement. And I > don't believe you did. Please read the whole changelog where I was quite verbose about how the current flag is abused and how its semantic is weak and encourages a wrong usage pattern. Moreover it is not even clear whether it helps anything. I haven't seen any actual counter argument from you other than "milliseconds not hours" without actually explaining how that would be useful for any decisions done in the core MM layer. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
