On Thu, Nov 17, 2016 at 03:24:35PM -0800, Song Liu wrote: > These are the 7th version of patches to enable write cache part of > raid5-cache. The journal part was released with kernel 4.4. > > The caching part uses same disk format of raid456 journal, and provides > acceleration to writes. Write operations are committed (bio_endio) once > the data is secured in journal. Reconstruct and RMW are postponed to > writing-out phase, which is usually not on the critical path. > > The changes are organized in 10 patches (details below). > > Patch for chunk_aligned_read in earlier RFC is not included yet > (http://marc.info/?l=linux-raid&m=146432700719277). But we may still need > some optimizations later, especially for SSD raid devices. > > Changes between v7 and v6 (http://marc.info/?l=linux-raid&m=147881079931937): > 1. Incorprate feedbacks; > 2. Modify representation of write-back state machine to use STRIPE_R5C_CACHING > instead of STRIPE_R5C_WRITE_OUT. This reduces state trasitions in > write-through mode; > 3. For prexor, allocate extra orig_page instead of page; > 4. Rename and refactor of some functions and variables; > 5. Remove path 11 (handle alloc_page failure). I will propose a simpler retry > patch later. Thanks for doing this, Song! And thanks Neil for the code review! I think this series are in good shape. We do have a lot of todo stuffes to make these work well, but we can always improve based on these. And since the default setting is write-through, there should be no regression (hopefully). I'm going to apply them to my for-next tree. If you have further bug fixes/improvements, please do them against the for-next tree. I don't apply the last patch though. That one doesn't work well for !write-back case (sorry, didn't notice it in last review), as for write-through, we don't need do any flush/fua. Please send an updated patch, I'll apply. I'll list the todo here so we don't forget: - makes read not enter state machine - write checkpoint block to make recovery faster - improve recovery - handle memory allocation failure - allow removing journal capability if journal disk fails And of course performance tuning. Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
