"Yang, Xiao/杨 晓" <yangx.jy@xxxxxxxxxxx> writes: > Hi Jeff, > > Thanks a lot for your reply. > > On 2022/9/27 3:52, Jeff Moyer wrote: >> "Yang, Xiao/杨 晓" <yangx.jy@xxxxxxxxxxx> writes: >> >>> Hi Ross, Toshi, Jeff and others >>> >>> After reading the kernel patches[1][2][3] about dm, I think only three >>> types(linear, stripe and log-writes) of dm can support DAX now, right? >> >> Right. >> >>> I wonder why only three types of dm need to support DAX? Is there any >>> reason/history and use case? >> >> It was easy to add DAX support to those targets. Note that if a target >> needs to intercept I/O, then it is fundamentally incompatible with DAX. > > How can I know which target needs to intercept I/O? There's no better way than reading and understanding what each target does. > Could you tell me why it is fundamentally incompatible with DAX? DAX stands for direct access, and it is a mechanism by which a user-space process can perform I/O without going through the kernel. -Jeff -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel
