Mikulas Patocka [mpatocka@xxxxxxxxxx] wrote: > Ideas how to fix it: > > 1. lock the buffers and unmap the pages while they are being written. > --- upstream developers would likely reject it. No other driver than > dm-raid1 has problems with this and they wouldn't damp performance because > of one driver. Very few drivers require it, so how about an interface to lock the pages of an I/O available to drivers. Only needed RAID drivers would lock the I/O while it is in progress and they only pay the performance penalty. mmap pages are a bit tricky. They need to go into read-only mode when an I/O is in progress. I know this would likely be rejected too!!! > 4. make more region states. > --- If the region is in RH_DIRTY state and all writes drain, the state is > changed to RH_MAYBE_DIRTY. (we don't know if the region is synchronized or > not). The disk dirty flag is kept. > --- periodically (once in few minutes, so that it doesn't affect > performance much), the change all regions in RH_MAYBE_DIRTY state to > RH_CLEAN_CANDIDATE, then issue sync() on all filesystems. If, after the > sync(), the region is still in RH_CLEAN_CANDIDATE (i.e. it hasn't been > written during the sync()), it is moved to RH_CLEAN state and the on-disk > bit for the region is turned off. Sounds good except that it uses sync()! Is there a way to sync only pages related to a certain block device? How hard it is to implement such an interface? --Malahal. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
