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[76.141.129.107]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6b9625f84d0sm46449586d6.45.2024.07.24.10.38.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jul 2024 10:38:29 -0700 (PDT) Date: Wed, 24 Jul 2024 12:38:27 -0500 From: David Vernet To: Peter Zijlstra Cc: Tejun Heo , Linus Torvalds , linux-kernel@vger.kernel.org, Ingo Molnar , Alexei Starovoitov , Thomas Gleixner Subject: Re: [GIT PULL] sched_ext: Initial pull request for v6.11 Message-ID: <20240724173827.GA281347@maniforge> References: <20240723163358.GM26750@noisy.programming.kicks-ass.net> <20240724085221.GO26750@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="0hVpz++H0BDlulKU" Content-Disposition: inline In-Reply-To: <20240724085221.GO26750@noisy.programming.kicks-ass.net> User-Agent: Mutt/2.2.13 (00d56288) (2024-03-09) --0hVpz++H0BDlulKU Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 24, 2024 at 10:52:21AM +0200, Peter Zijlstra wrote: [...] > > > Also, why does that thing hard depend on DEBUG_BTF? (at least having > > > that option enabled no longer explodes build times like it used to) > >=20 > > That's necessary for building the schedulers, at least, I think. We did= n't > > have that earlier and people were getting confused. >=20 > It's what made it difficult for me to even build this stuff, simple > things like: >=20 > cd foo-build; ../scipts/config --enable CONFIG_SCHED_CLASS_EXT; cd - >=20 > don't work (nor error out on the lack of dependencies), and my build > scripts were force disabling the BTF crud -- and thus silently also the > scx thing. >=20 > It looks like I can change my builds scripts, because the reason I did > that was that BTF made the build times explode and that is no longer the > case. Yeah so to clarify the situation here -- BTF is a hard requirement for sched_ext because BPF requires it in order to call kfuncs [0] (note that the APIs have changed significantly since that article was written). The reason it's required, among other things, is so that the verifier can check that a BPF prog is safely invoking a kernel function with the proper types. [0]: https://lwn.net/Articles/856005/ --0hVpz++H0BDlulKU Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEARYKAB0WIQRBxU1So5MTLwphjdFZ5LhpZcTzZAUCZqE8EwAKCRBZ5LhpZcTz ZCqOAP9LiaxIMZ+n824HtZp0/SDiV1zApJQsEIY13FiJcanHtQD/TMLZ4Rsz5gTS /HuQWhjmw2P8YLcA9gqsomZlxnBZzQ0= =GIVF -----END PGP SIGNATURE----- --0hVpz++H0BDlulKU--