On Thu, Dec 18 2014 at 10:37am -0500, Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > On Wed, Dec 17 2014 at 7:40pm -0500, > Timofey Titovets <nefelim4ag@xxxxxxxxx> wrote: > > > io_schedule_timeout(5*HZ); > > Introduced for avoidance dm bug: > > http://linux.derkeiler.com/Mailing-Lists/Kernel/2006-08/msg04869.html > > According to description must be replaced with io_schedule() > > > > Can you test it and answer: it produce any regression? > > > > I replace it and recompile kernel, tested it by following script: > > --- > > dev="" > > block_dev=zram #loop > > if [ "$block_dev" == "loop" ]; then > > f1=$RANDOM > > f2=${f1}_2 > > truncate -s 256G ./$f1 > > truncate -s 256G ./$f2 > > dev="$(losetup -f --show ./$f1) $(losetup -f --show ./$f2)" > > rm ./$f1 ./$f2 > > else > > modprobe zram num_devices=8 > > # needed ~1g free ram for test > > echo 128G > /sys/block/zram7/disksize > > echo 128G > /sys/block/zram6/disksize > > dev="/dev/zram7 /dev/zram6" > > fi > > > > md=/dev/md$[$RANDOM%8] > > echo "y\n" | mdadm --create $md --chunk=4 --level=1 --raid-devices=2 $(echo $dev) > > You didn't test using DM, you used MD. > > And in the context of 2.6.18 the old dm-raid1 target was all DM had > (whereas now we also have a DM wrapper around MD raid with the dm-raid > module). Should we just kill dm-raid1 now that we have dm-raid? But > that is tangential to the question being posed here. Heinz pointed out that dm-raid1 handles clustered raid1 capabilities. So we cannot easily replace with dm-raid. > So I'll have to read the thread you linked to to understand if DM raid1 > (or DM core) still suffers from the problem that this hack papered over. Heinz also pointed out that the primary issue that forced the use of io_schedule_timeout() was that dm-log-userspace (used by dm-raid1) makes use of a single shared mempool for multiple devices. Unfortunately, dm-log-userspace still has this shared mempool (flush_entry_pool). So we'll need to fix that up to be per-device before mm/mempool.c code can be switched to use io_schedule(). I'll add this to my TODO. But it'll have to wait until after the new year. Mike -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
