[PATCH V2 02/12] nvmet: for pt I/O commands use likely for ns check

Christoph Hellwig hch at lst.de
Thu Sep 3 12:18:05 EDT 2020


On Mon, Aug 31, 2020 at 03:26:57PM -0700, Chaitanya Kulkarni wrote:
> I/O commands (nvme_cmd_read, nvme_cmd_write) are most common commands
> when accessing passthru controller. Since for I/O commands ns is always
> present and the condition is marked as likely. Annotate post request
> submission ns check with likely which is dependent on earlier the ns
> check likely condition.

This really seems like weird over-optimization.  Any sensible branch
predictor should be able to find this out by itself.



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