Apple M1/Apple Silicon/arm64 macOS can run x86_64 programs via Rosetta and most M1 systems currently (~March 2021) very likely run a mix of x86_64 and arm64 processes.

Activity Monitor can show the architecture:

but command line tools such as ps and top do not due to Apple hiding the details of the proper sysctl() incantations necessary to get this info.

Patrick Wardle reverse engineered Activity Monitor — https://www.patreon.com/posts/45121749 — and I slapped that hack together with some code from Sydney San Martin — https://gist.github.com/s4y/1173880/9ea0ed9b8a55c23f10ecb67ce288e09f08d9d1e5 — into a nascent, bare-bones command line utility: archinfo.

It returns columnar output or JSON (via --json) — that will work nicely with jq — of running processes and their respective architectures.

Build from source or grab from the releases via my git (https://git.rud.is/hrbrmstr/archinfo) or GH (https://github.com/hrbrmstr/archinfo).

$ archinfo
...
   5949  arm64 /System/Library/Frameworks/AudioToolbox.framework/AudioComponentRegistrar
   5923  arm64 /System/Library/CoreServices/LocationMenu.app/Contents/MacOS/LocationMenu
   5901 x86_64 /Library/Application Support/Adobe/Adobe Desktop Common/IPCBox/AdobeIPCBroker.app/Contents/MacOS/AdobeIPCBroker
   5873  arm64 /Applications/Utilities/Adobe Creative Cloud Experience/CCXProcess/CCXProcess.app/Contents/MacOS/../libs/Adobe_CCXProcess.node
   5863  arm64 /bin/sleep
   5861 x86_64 /Applications/Tailscale.app/Contents/PlugIns/IPNExtension.appex/Contents/MacOS/IPNExtension
   5855 x86_64 /Applications/Elgato Control Center.app/Contents/MacOS/Elgato Control Center
   5852 x86_64 /Applications/Tailscale.app/Contents/MacOS/Tailscale
   5849  arm64 /System/Library/CoreServices/TextInputSwitcher.app/Contents/MacOS/TextInputSwitcher
...

library(tidyverse)

arch <- jsonlite::stream_in(textConnection(system("/usr/local/bin/archinfo --json", intern=TRUE)))

arch %>% 
  as_tibble() %>% 
  mutate(
    name = basename(name)
  ) %>% 
  select(
    name, arch
  ) 
## # A tibble: 448 x 2
##    executable                                          arch
##    <chr>                                               <chr>
## ...
## 50 com.apple.WebKit.WebContent                         arm64
## 51 com.apple.WebKit.Networking                         arm64
## 52 com.apple.WebKit.WebContent                         arm64
## 53 RStudio — tycho                                     x86_64
## 54 QtWebEngineProcess                                  x86_64
## 55 VTEncoderXPCService                                 arm64
## 56 rsession-arm64                                      arm64
## 57 RStudio                                             x86_64
## 58 MTLCompilerService                                  arm64
## 59 MTLCompilerService                                  arm64
## 60 coreautha                                           arm64
## ...

table(arch[["arch"]])
##
##  arm64 x86_64
##    419     29

UPDATE 2021-03-14

My original goal was to use Swift for this, but it dawned on me that the vast majority of the codebase is in C, so I’ve removed the Xcode dependency and simplified the build process.

The updated code also now defaults to columnar output. Use --json to return ndjson output.