On Fri, Mar 17, 2017, at 01:12 PM, Chris Peterson wrote: > On 3/17/2017 1:45 AM, Honza Bambas wrote: > > I have a very similar setup, with even way more exceptions added, but > > none of them has the desired effect. Unfortunately, the only way to make > > MsMpEng shut up is to disable run-time protection completely for the > > time of the build. I think it's a bug in Defender. > > Maybe `mach build` can temporarily disable Defender when building?
You can't programmatically control Windows Defender, even as an Administrator. This is a security precaution from Microsoft. It's configured with a special user account. I looked into this recently because I thought it would be nice if *something* in the build system or bootstrap could at least let you know if your build directories were not in the list of exclusions. Back to the original topic, I recently set up a fresh Windows machine and I followed the same basic steps (enable performance power mode, whitelist a bunch of stuff in Windows Defender) and my build seemed basically CPU-bound[1] during the compile tier. Disabling realtime protection in Defender made it *slightly* better[2] but didn't have a large impact on the overall build time (something like 20s out of ~14m total for a clobber). Ideally we should have this stuff as part of `mach bootstrap` or similar so everyone gets their machine configured properly for the fastest builds possible. Related, my next steps were that I was planning to figure out how to gather an xperf profile of the entire build process to see if there were any obvious speedups left from a system perspective (the resource usage graph shows the obvious inefficiencies left that are already known: configure + the non-compile tiers), but UIforETW hung when I tried to use it to do so and I haven't followed up yet. -Ted 1. http://people.mozilla.org/~tmielczarek/build-resource-usage.svg 2. https://people-mozilla.org/~tmielczarek/build-resource-usage-no-defender.svg _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
