shrink low-bandwidth pipes under Linux

I've hit /proc/sys/fs/pipe-user-pages-* limits on some systems.
So stop hogging resources on pipes which don't benefit from
giant sizes.

Some of these can use eventfd in the future to further reduce
resource use.

1 files changed, 5 insertions, 0 deletions

diff --git a/lib/PublicInbox/Daemon.pm b/lib/PublicInbox/Daemon.pm
index 4629aadb..6d2ae81b 100644
--- a/lib/PublicInbox/Daemon.pm
+++ b/lib/PublicInbox/Daemon.pm
@@ -356,6 +356,11 @@ sub unlink_pid_file_safe_ish ($$) {
 sub master_loop {
         pipe(my ($p0, $p1)) or die "failed to create parent-pipe: $!";
         pipe(my ($r, $w)) or die "failed to create self-pipe: $!";
+
+        if ($^O eq 'linux') { # 1031: F_SETPIPE_SZ = 1031
+                fcntl($_, 1031, 4096) for ($w, $p1);
+        }
+
         IO::Handle::blocking($w, 0);
         my $set_workers = $worker_processes;
         my @caught;