> Le 16 sept. 2016 à 17:23, Jens Axboe <axboe@xxxxxxxxx> a écrit : > > On 09/15/2016 08:23 AM, Fabrice Bacchella wrote: >> >> Is there any plan to support it ? > > What kind of use case did you have in mind? Dropping pages after writing > them? That basically boils down to being a non data integrity fdatasync. > You would get basically the same effect by using fdatasync=1 in your > workload. The difference would mainly be that DONTNEED would factor in > the range and offset. So if you have multiple writers on the same file, > then there would be a difference in behavior. > > That said, I don't mind adding support for using DONTNEED specifically. > Currently it's just used to set a permanent hint, which is why it's only > done once. For DONTNEED, you'd want to call it after each write instead. I was thinking about read. When you have servers with huge amount of memory, either you reboot then with mem=<less>G or run bench with huge datasets. Both are clumsy solutions. directio is not a very good solution either, it's a very specific think that don't match not cached data. Using DONTNEED allows to simulate (I hope) a "bigger that RAM" data set. -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
