This problem occurs with emacs 26.3 but didn't occur with 25.x. Possibly related to bug#33194. My hypothesis is that emacs is monitoring some files that it shouldn't but I need some help in figuring out which files are being monitored and whether that is indeed a bug. When I run a CPU-bound job that also does quite a bit of I/O, emacs becomes very unresponsive -- running "top", I see CPU usage for emacs go into the 50-100% range. (Ubuntu 18.04, emacs 26.3 on a 4-CPU machine with SSD disk) The job I'm running is parallel -v --will-cite --keep-order --group -L80 -j8 (the problem does not go away when I change to "-j3") As far as I know, I don't have any of the output files or directories open (I have global-auto-revert-mode set) -- all the outputs go into one directory and when I search the Buffer List, I don't see that directory. I upgraded from emacs 25.3 to 26.3 today, with the same .emacs.desktop, and the problem wasn't showing with emacs 25.3. I double-checked the output of lsof on one of the running CPU processes and again couldn't find anything that matched with the Emacs buffer. However, I did notice that file-name-history did match some. Any suggestions on how to track down what's causing the polling? As I mentioned, this didn't happen with emacs 25.3 with the same files open. It also doesn't happen when I start 26.3 without the .emacs.desktop (that is, with nothing in the Buffer List). "strace -c" emacs when not running the CPU/IO job: % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 31.63 0.009027 3 2950 2534 recvmsg 23.19 0.006618 3 2057 poll 13.38 0.003819 3 1100 rt_sigprocmask 12.10 0.003454 17 209 pselect6 9.17 0.002618 6 466 writev 7.62 0.002174 5 405 rt_sigreturn 1.21 0.000344 57 6 openat 0.37 0.000105 4 30 1 read 0.31 0.000089 3 26 timerfd_settime 0.28 0.000080 11 7 ioctl 0.22 0.000064 64 1 vfork 0.11 0.000032 11 3 fcntl 0.11 0.000030 4 8 close 0.09 0.000026 1 51 9 stat 0.06 0.000017 17 1 pipe2 0.06 0.000016 0 48 11 faccessat 0.04 0.000011 11 1 getuid 0.03 0.000009 5 2 wait4 0.01 0.000003 1 4 write 0.00 0.000000 0 3 fstat 0.00 0.000000 0 3 lseek 0.00 0.000000 0 1 inotify_add_watch 0.00 0.000000 0 1 1 readlinkat ------ ----------- ----------- --------- --------- ---------------- 100.00 0.028536 7383 2556 total "strace -c" emacs when running the CPU/IO job: % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 30.79 0.013978 1 15384 poll 21.05 0.009554 1 15799 12395 recvmsg 19.44 0.008827 1 6538 writev 13.96 0.006339 1 12446 rt_sigprocmask 6.97 0.003162 2 1554 pselect6 2.96 0.001342 0 3108 rt_sigreturn 2.95 0.001338 1 1551 read 1.88 0.000855 1 1551 ioctl 0.00 0.000000 0 10 stat 0.00 0.000000 0 1 restart_syscall 0.00 0.000000 0 10 faccessat ------ ----------- ----------- --------- --------- ---------------- 100.00 0.045395 57952 12395 total "strace -c emacs when running the CPU/IO job without global-auto-revert-mode: % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 37.41 0.001833 1 1860 1576 recvmsg 27.88 0.001366 1 1619 poll 14.78 0.000724 5 142 pselect6 7.43 0.000364 2 201 writev 6.29 0.000308 1 570 rt_sigprocmask 6.06 0.000297 1 318 24 rt_sigreturn 0.08 0.000004 1 6 write 0.06 0.000003 0 8 read 0.02 0.000001 1 2 openat 0.00 0.000000 0 2 close 0.00 0.000000 0 6 3 recvfrom 0.00 0.000000 0 1 1 faccessat ------ ----------- ----------- --------- --------- ---------------- 100.00 0.004900 4735 1604 total In GNU Emacs 26.3 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.22.30) of 2019-09-16 built on lcy01-amd64-030 Windowing system distributor 'The X.Org Foundation', version 11.0.11906000 System Description: Ubuntu 18.04.3 LTS Recent messages: Making completion list... Saving file /tmp/t10.kythe.json-decoded... Wrote /tmp/t10.kythe.json-decoded Quit [5 times] command-execute: Buffer is read-only: # Mark set Quit Mark saved where search started Quit [2 times] Mark saved where search started [2 times] Quit [4 times] Configured using: 'configure --build=x86_64-linux-gnu --prefix=/usr '--includedir=${prefix}/include' '--mandir=${prefix}/share/man' '--infodir=${prefix}/share/info' --sysconfdir=/etc --localstatedir=/var --disable-silent-rules '--libdir=${prefix}/lib/x86_64-linux-gnu' '--libexecdir=${prefix}/lib/x86_64-linux-gnu' --disable-maintainer-mode --disable-dependency-tracking --prefix=/usr --sharedstatedir=/var/lib --program-suffix=26 --with-modules --with-file-notification=inotify --with-mailutils --with-x=yes --with-x-toolkit=gtk3 --with-xwidgets --with-lcms2 'CFLAGS=-g -O2 -fdebug-prefix-map=/build/emacs26-TP6iDo/emacs26-26.3~1.git96dd019=. -fstack-protector-strong -Wformat -Werror=format-security -no-pie' 'CPPFLAGS=-Wdate-time -D_FORTIFY_SOURCE=2' 'LDFLAGS=-Wl,-Bsymbolic-functions 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hides /usr/share/emacs/26.3/lisp/progmodes/prolog /usr/share/emacs/site-lisp/latex-cjk-thai/thai-word hides /usr/share/emacs/26.3/lisp/language/thai-word Features: (shadow mail-extr emacsbug sendmail eieio-opt speedbar sb-image ezimage dframe find-func completion help-fns tabify man novice pulse misearch multi-isearch solarized dash quail inf-haskell haskell-decl-scan haskell haskell-completions haskell-load haskell-commands highlight-uses-mode haskell-modules haskell-sandbox haskell-repl haskell-debug haskell-interactive-mode haskell-presentation-mode haskell-collapse haskell-navigate-imports haskell-compile haskell-process haskell-session haskell-hoogle edmacro kmacro sort autoload radix-tree cl-extra lisp-mnt help-mode mm-archive network-stream starttls url-http tls gnutls url-gw nsm url-cache url-auth vc vc-dispatcher server erlang tempo cl perl-mode asm-mode conf-mode jka-compr add-log rst haskell-mode haskell-cabal haskell-utils haskell-font-lock haskell-indentation 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minibuffer cl-preloaded nadvice loaddefs button faces cus-face macroexp files text-properties overlay sha1 md5 base64 format env code-pages mule custom widget hashtable-print-readable backquote threads dbusbind inotify lcms2 dynamic-setting system-font-setting font-render-setting xwidget-internal move-toolbar gtk x-toolkit x multi-tty make-network-process emacs) Memory information: ((conses 16 791439 152674) (symbols 48 44537 1) (miscs 40 2000 2396) (strings 32 134121 30613) (string-bytes 1 6691533) (vectors 16 70253) (vector-slots 8 1997947 168512) (floats 8 365 431) (intervals 56 50166 2906) (buffers 992 501))