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[83.51.215.31]) by smtp.gmail.com with ESMTPSA id c22sm6283276wmb.10.2021.05.21.07.21.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 21 May 2021 07:21:08 -0700 (PDT) Subject: Re: [PATCH v3 4/6] gitlab-ci: Add ccache in $PATH and display statistics To: =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= References: <20210519184549.2192728-1-f4bug@amsat.org> <20210519184549.2192728-5-f4bug@amsat.org> <5a77ade3-1a6c-2389-4a1c-2c7c2266f298@redhat.com> <20c001a0-60ed-df08-b67d-884022e74d04@amsat.org> <396e75d2-fe22-3054-fbee-d6de02339b2a@redhat.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Message-ID: Date: Fri, 21 May 2021 16:21:07 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::330; envelope-from=philippe.mathieu.daude@gmail.com; helo=mail-wm1-x330.google.com X-Spam_score_int: -14 X-Spam_score: -1.5 X-Spam_bar: - X-Spam_report: (-1.5 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FORGED_FROMDOMAIN=0.25, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.25, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Huth , Kyle Evans , qemu-devel@nongnu.org, Wainer dos Santos Moschetta , Willian Rampazzo , Stefan Hajnoczi , =?UTF-8?Q?Alex_Benn=c3=a9e?= , Warner Losh Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 5/21/21 2:52 PM, Daniel P. Berrangé wrote: > On Fri, May 21, 2021 at 02:27:26PM +0200, Philippe Mathieu-Daudé wrote: >> On 5/21/21 1:53 PM, Daniel P. Berrangé wrote: >>> On Fri, May 21, 2021 at 01:02:51PM +0200, Thomas Huth wrote: >>>> On 21/05/2021 12.50, Daniel P. Berrangé wrote: >>>>> On Fri, May 21, 2021 at 12:48:21PM +0200, Thomas Huth wrote: >>>>>> On 20/05/2021 13.27, Philippe Mathieu-Daudé wrote: >>>>>>> +Stefan/Daniel >>>>>>> >>>>>>> On 5/20/21 10:02 AM, Thomas Huth wrote: >>>>>>>> On 19/05/2021 20.45, Philippe Mathieu-Daudé wrote: >>>>>>>>> If a runner has ccache installed, use it and display statistics >>>>>>>>> at the end of the build. >>>>>>>>> >>>>>>>>> Signed-off-by: Philippe Mathieu-Daudé >>>>>>>>> --- >>>>>>>>>   .gitlab-ci.d/buildtest-template.yml | 5 +++++ >>>>>>>>>   1 file changed, 5 insertions(+) >>>>>>>>> >>>>>>>>> diff --git a/.gitlab-ci.d/buildtest-template.yml >>>>>>>>> b/.gitlab-ci.d/buildtest-template.yml >>>>>>>>> index f284d7a0eec..a625c697d3b 100644 >>>>>>>>> --- a/.gitlab-ci.d/buildtest-template.yml >>>>>>>>> +++ b/.gitlab-ci.d/buildtest-template.yml >>>>>>>>> @@ -6,13 +6,18 @@ >>>>>>>>>         then >>>>>>>>>           JOBS=$(sysctl -n hw.ncpu) >>>>>>>>>           MAKE=gmake >>>>>>>>> +        PATH=/usr/local/libexec/ccache:$PATH >>>>>>>>>           ; >>>>>>>>>         else >>>>>>>>>           JOBS=$(expr $(nproc) + 1) >>>>>>>>>           MAKE=make >>>>>>>>> +        PATH=/usr/lib/ccache:/usr/lib64/ccache:$PATH >>>>>>>> >>>>>>>> That does not make sense for the shared runners yet. We first need >>>>>>>> something to enable the caching there - see my series "Use ccache in the >>>>>>>> gitlab-CI" from April (which is currently stalled unfortunately). >>>>>>> >>>>>>> TL;DR: I don't think we should restrict our templates to shared runners. >>>>>> >>>>>> I'm certainly not voting for restricting ourselves to only use shared >>>>>> runners here - but my concern is that this actually *slows* down the shared >>>>>> runners even more! (sorry, I should have elaborated on that in my previous >>>>>> mail already) >>>>>> >>>>>> When I was experimenting with ccache in the shared runners, I saw that the >>>>>> jobs are running even slower with ccache enabled as long as the cache is not >>>>>> populated yet. You only get a speedup afterwards. So if you add this now >>>>>> without also adding the possibility to store the cache persistently, the >>>>>> shared runners will try to populate the cache each time just to throw away >>>>>> the results afterwards again. Thus all the shared runners only get slower >>>>>> without any real benefit here. >>>>>> >>>>>> Thus we either need to get ccache working properly for the shared runners >>>>>> first, or you have to think of a different way of enabling ccache for the >>>>>> non-shared runners, so that it does not affect the shared runners >>>>>> negatively. >>>>> >>>>> Is there anything functional holding up your previous full cccache support >>>>> series from last month ? Or is it just lack of reviews ? >>>> >>>> It's basically the problems mentioned in the cover letter and Stefan's >>>> comment here: >>>> >>>> https://lists.gnu.org/archive/html/qemu-devel/2021-04/msg02219.html >>> >>> I'm not sure I understand why Stefan thinks gitlab's caching doesn't >>> benefit ccache. We add ccache for libvirt GitLab CI, and AFAIR it >>> sped up our builds significantly. >> >> I think Stefan is referring to a comment I made, when using both >> shared runners and dedicated runners (what I'm currently testing) >> various jobs are stuck transferring artifacts/cache {FROM, TO} >> {shared, dedicated} runners at the same time, which is sub-optimal >> because it saturate the dedicated runner network link. > > I think we're over thinking things a bit too much and worrying about > scenarios that we're not actually hitting that frequently today, and > delaying the benefit for everyone. > > Our common case is that most contributors are simply using shared > runners exclusively, as is the main qemu repo staging branch. AFAIK > these should benefit from a simple ccache enablement today. > > Since there are questions about other setups though, we can just > provide an easy way to turn it off. eg: > > if test -z "$QEMU_CI_SKIP_CCACHE" > then > PATH=/usr/local/libexec/ccache:$PATH > fi > > anyone who wishes to disable it, can just set that variable in their > git repo fork. If there are specific jobs we want to disable cccache > for, those jobs can set that too. OK, understood. I'll see with Willian how to have ccache working. Thanks for the feedback, Phil.