On 8/27/20 8:04 AM, Damien Le Moal wrote: > On 2020/08/27 23:51, Randy Dunlap wrote: >> On 8/27/20 6:50 AM, Niklas Cassel wrote: >>> Add support for user space to set a max open zone and a max active zone >>> limit via configfs. By default, the default values are 0 == no limit. >> >> Hi, >> >> How does a user find out about how to use/set these limits? > > For the setting part, this is for testing. So any value, even extreme ones (e.g. > 1) would be OK to check that a software correctly handles write accesses to > zones for a device that has open/active zone limitations. A more practical way > is to reuse values of real devices. For instance, some SMR disks I use have a > max open limit of 128 and max active 0 (there is no limit for active zones on > SMR disks as ZBC/ZAC specifications do not define this concept). > > Another example is our soon to come work on btrfs zone support which shows that > at the very least 6 active zones are needed. So tests can be performed with that > minimum to check the file system and that its block allocator does not go > opening/activating too many zones. > > For the using part, the above btrfs example is good: if the FS tries to allocate > blocks in too many inactive zones at the same time without first filling out > zones already active, it may exceed the limit and writes will fail. The FS must > thus be aware of the limits and its block al;locator tuned to limit block > allocations within a set of zones smaller than the maximum active limit. > > Does this answer your question ? Yes. Thank you. -- ~Randy
