On Sun, Oct 4, 2015 at 12:52 AM, Ming Lei <tom.leim...@gmail.com> wrote: > On Wed, Sep 30, 2015 at 8:41 AM, Dan Williams <dan.j.willi...@intel.com> > wrote: >> Allow pmem, and other synchronous/bio-based block drivers, to fallback > > Just a bit curious, why not extend it for all(both synchronous and > asynchrounous) bio-based drivers? As you mentioned in introductory > message, all bio based drivers may have this kind of problem. > > One idea I thought of is to hold the usage counter in bio life time, > instead of request's life time like in blk-mq. > >> on a per-cpu reference count managed by the core for tracking queue >> live/dead state. >> >> The existing per-cpu reference count for the blk_mq case is promoted to >> be used in all block i/o scenarios. This involves initializing it by >> default, waiting for it to drop to zero at exit, and holding a live >> reference over the invocation of q->make_request_fn() in > > It isn't enough for asynchrounous bio drivers.
True, but I think that support is a follow on extension of the mechanism. It seems to me not as straightforward as holding a per-request reference or a reference over the submission path. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
