On Sat, Nov 26, 2016 at 9:31 AM, Ehsan Akhgari <ehsan.akhg...@gmail.com> wrote:
> On 2016-11-24 7:04 PM, Nathan Froyd wrote: > > On Wed, Nov 23, 2016 at 4:31 PM, Mike Hommey <m...@glandium.org> wrote: > >> I know OSX can be bad with I/O, but that seems unusually bad. IIRC gps > >> found that there's a relatively low limit to the number of files or > >> inodes that can be in cache, and a working tree of m-c alone is close > >> to the limit, so changing that configuration could help. > > > > Is this the ken.maxvnodes sysctl setting? You can change it for your > > current session with: > > > > sudo sysctl kern.maxvnodes=$((512*1024)) > > > > You may want to experiment with higher settings depending on RAM, etc. > > You can change it permanently with: > > > > echo kern.maxvnodes=$((512*1024)) | sudo tee -a /etc/sysctl.conf > > > > (settings per https://chromium.googlesource.com/chromium/src/+/master/ > docs/mac_build_instructions.md#Improving-performance-of) > > > > I've found on my (several years old) Mac that changing this setting > > does indeed make a significant performance difference. > > Thank you! > > Doing this reduced the "reading moz.build files" stage of build-backend > down to about 14s, reliably every time. That seems to suggest that > everything now fits into the cache (I'm now experimenting with a higher > value since I have tons of unused RAM.) > > The entire runtime of build-backend now on an unchanged tree is about > 25-28s, which is much higher than I would like... :( > I'm very glad to hear things are running faster! However, I find it *really* difficult to believe that moz.build reading alone was enough to exhaust the default vnode cache. On Linux (where results should be comparable), `strace -e trace=file` says `mach build-backend` accesses 72609 unique paths across ~300k recorded function calls. Even if you count inodes for directories, we shouldn't be near the 256k default limit and immediate subsequent config.status runs should not run into cache eviction issues. There's got to be something funky about your machine or build configuration :/
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