From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Brown Subject: Re: [PATCH 1/4] spi: For controllers that need realtime always use the pump thread Date: Sun, 12 May 2019 16:33:01 +0900 Message-ID: <20190512073301.GC21483@sirena.org.uk> References: <20190510223437.84368-1-dianders@chromium.org> <20190510223437.84368-2-dianders@chromium.org> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============7376112348469151644==" Cc: drinkcat-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org, briannorris-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-rockchip-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, mka-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org, Enric Balletbo i Serra , Guenter Roeck , Benson Leung To: Douglas Anderson Return-path: In-Reply-To: <20190510223437.84368-2-dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-rockchip" Errors-To: linux-rockchip-bounces+glpar-linux-rockchip=m.gmane.org-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: linux-spi.vger.kernel.org --===============7376112348469151644== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="/e2eDi0V/xtL+Mc8" Content-Disposition: inline --/e2eDi0V/xtL+Mc8 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, May 10, 2019 at 03:34:34PM -0700, Douglas Anderson wrote: > If a controller specifies that it needs high priority for sending > messages we should always schedule our transfers on the thread. If we > don't do this we'll do the transfer in the caller's context which > might not be very high priority. If performance is important you probably also want to avoid the context thrashing - executing in the calling context is generally a substantial performance boost. I can see this causing problems further down the line when someone else turns up with a different requirement, perhaps in an application where the caller does actually have a raised priority themselves and just wanted to make sure that the thread wasn't lower than they are. I guess it'd be nice if we could check what priority the calling thread has and make a decision based on that but there don't seem to be any facilities for doing that which I can see right now. --/e2eDi0V/xtL+Mc8 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAlzXzCcACgkQJNaLcl1U h9AjOAf+MXPHyjoQyfbJn08k/H8FZGylRFAxKaq4gxN0q4GV4ErRQ4izUJ80gQ5U sCbdavMU+2u2yZ8yl/uthfJzXlmpViMGmi/nnHwRcPunHFz1nBmA9sZ4/ODkIj8N cCWjLrCRxeE9e23yjIInTgiMkgg2DgSeA+0kVbtg4S0gyIM+POpLXtN6thC9bi0N +ZVukER12euMeuVoruZ9jAo52XBhVjj2tpFK18N+bbgIMKB1T2qrd1Fp2r3H6+ty GQsyEb/f1XN0NXaLDI5wunSFe0EiUe6P6rZuu4p9ZTyPhg663C+JsqU72Rj8EBXA qT+vCFKYWKPzapEj1LDuT9p+DyPnyg== =aJHR -----END PGP SIGNATURE----- --/e2eDi0V/xtL+Mc8-- --===============7376112348469151644== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Linux-rockchip mailing list Linux-rockchip-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org http://lists.infradead.org/mailman/listinfo/linux-rockchip --===============7376112348469151644==--