Re: [RFC PATCH] locking/percpu-rwsem: use this_cpu_{inc|dec}() for read_count

Christoph Hellwig
2020-09-17T14:58:51Z

On Thu, Sep 17, 2020 at 04:46:38PM +0300, Boaz Harrosh wrote:
> From my totally subjective experience on the filesystem side (user of
> bio_endio) all HW block drivers I used including Nvme isci, sata... etc. end
> up calling bio_endio in softirq. The big exception to that is the vdX
> drivers under KVM. Which is very Ironic to me.

NVMe normally calls it from hardirq or IPI context. The only time it
would use softirq context is if you have a single I/O queue, which is
very unusual.