From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.5 required=3.0 tests=DATE_IN_PAST_06_12, DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI, SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6067CC04AB3 for ; Sun, 12 May 2019 17:06:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 33F502173B for ; Sun, 12 May 2019 17:06:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557680784; bh=oYcG401Dw5xc0PDiEu/wofuk2A2xabz1Swz0kNe5TQo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=jufcjkdDmW482qu2ZXq+0oBnnPuBSIHBd3v8LmTFX23uZmqXqStA0D7eLh3bY0yRG GLwUAjssiZ9Y5+cNEwoiEWPTB6eYeWmz8Y1ha8MedA6kIIieBOXnczAtH7wPoEDkGi f8IUDz5JonkLyQpaJ/myNW2o/sFJ49dVbGd1qsAw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727152AbfELRGX (ORCPT ); Sun, 12 May 2019 13:06:23 -0400 Received: from heliosphere.sirena.org.uk ([172.104.155.198]:49570 "EHLO heliosphere.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726857AbfELRFt (ORCPT ); Sun, 12 May 2019 13:05:49 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sirena.org.uk; s=20170815-heliosphere; h=In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=JGyDpXs0z4qP/VLm+QIIvl6tLAm7ZejvyxnTMOgb8/o=; b=kPQ9K/GcuDxCVWrz7TmQZp9qq uWbtRKu5SSeuFIwTtJ5d4MgiHwpuqoLAndskrb2iTEFu8Oy0KiEKGW9bJtjSm09or+/MMBizPkRjh xZ80jRTm/E1gPRhYoiX0p7977HVfVdo76T9WcZCaiG+QNMAvdXQlpqpb2QcZ/OGfCksrw=; Received: from [81.145.206.43] (helo=finisterre.sirena.org.uk) by heliosphere.sirena.org.uk with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hPruu-00044g-9y; Sun, 12 May 2019 17:05:40 +0000 Received: by finisterre.sirena.org.uk (Postfix, from userid 1000) id 44E0644000C; Sun, 12 May 2019 08:33:01 +0100 (BST) Date: Sun, 12 May 2019 16:33:01 +0900 From: Mark Brown To: Douglas Anderson Cc: Benson Leung , Enric Balletbo i Serra , linux-rockchip@lists.infradead.org, drinkcat@chromium.org, Guenter Roeck , briannorris@chromium.org, mka@chromium.org, linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org Subject: Re: [PATCH 1/4] spi: For controllers that need realtime always use the pump thread 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/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="/e2eDi0V/xtL+Mc8" Content-Disposition: inline In-Reply-To: <20190510223437.84368-2-dianders@chromium.org> X-Cookie: HOST SYSTEM RESPONDING, PROBABLY UP... User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --/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--