On Tue, Jul 14 2015 at 2:48pm -0400, Jens Axboe <[email protected]> wrote:
> Lots of devices exhibit very high latencies for big discards, hurting > reads and writes. By default, limit the max discard we will build to > 64MB. This value has shown good results across a number of devices. > > This will potentially hurt discard throughput, from a provisioning > point of view (when the user does mkfs.xfs, for instance, and mkfs > issues a full device discard). If that becomes an issue, we could > have different behavior for provisioning vs runtime discards. > > Signed-off-by: Jens Axboe <[email protected]> Christoph suggested you impose this default for the specific drivers/devices that benefit. I'm not following why imposing a 64MB default is the right thing to do for all devices. If this goes in I know for sure I'll need to work around it in DM-thinp. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
