lib/PublicInbox/Daemon.pm     | 5 +++++
 lib/PublicInbox/EvCleanup.pm  | 4 ++++
 lib/PublicInbox/Git.pm        | 4 ++++
 lib/PublicInbox/V2Writable.pm | 3 +++

diff --git a/lib/PublicInbox/Daemon.pm b/lib/PublicInbox/Daemon.pm
index 4629aadb45ec070332ef20d93673409301409d3d..6d2ae81bc1694dcc3c9fbf1ae2cbf7b249c3153d 100644
--- a/lib/PublicInbox/Daemon.pm
+++ b/lib/PublicInbox/Daemon.pm
@@ -356,6 +356,11 @@
 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;
diff --git a/lib/PublicInbox/EvCleanup.pm b/lib/PublicInbox/EvCleanup.pm
index 1a3a3d5e7735b6d8a3f2a12cd6ff4cc2ac7e3500..1a2bdb294a6431a38cb79f7fa69273c6bbf19653 100644
--- a/lib/PublicInbox/EvCleanup.pm
+++ b/lib/PublicInbox/EvCleanup.pm
@@ -19,7 +19,11 @@
 sub once_init () {
 	my $self = fields::new('PublicInbox::EvCleanup');
 	my ($r, $w);
+
+	# This is a dummy pipe which is always writable so it can always
+	# fires in the next event loop iteration.
 	pipe($r, $w) or die "pipe: $!";
+	fcntl($w, 1031, 4096) if $^O eq 'linux'; # 1031: F_SETPIPE_SZ
 	$self->SUPER::new($w);
 	$self->{rd} = $r; # never read, since we never write..
 	$self;
diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index 95df52ed6f2fd9f2b058d404d4358acebf0532c2..16117277079e86b6aecfc4291a3cf90e25928c0a 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -37,6 +37,10 @@ 	my ($in_r, $in_w, $out_r, $out_w);
 
 	pipe($in_r, $in_w) or fail($self, "pipe failed: $!");
 	pipe($out_r, $out_w) or fail($self, "pipe failed: $!");
+	if ($^O eq 'linux') { # 1031: F_SETPIPE_SZ
+		fcntl($out_w, 1031, 4096);
+		fcntl($in_w, 1031, 4096) if $batch eq '--batch-check';
+	}
 
 	my @cmd = ('git', "--git-dir=$self->{git_dir}", qw(cat-file), $batch);
 	my $redir = { 0 => fileno($out_r), 1 => fileno($in_w) };
diff --git a/lib/PublicInbox/V2Writable.pm b/lib/PublicInbox/V2Writable.pm
index 0a304aae241a6b390592b30b3f21ddfeb608de9b..fbab8f70be8a3233f0b4cc2a6d776e7c02c13244 100644
--- a/lib/PublicInbox/V2Writable.pm
+++ b/lib/PublicInbox/V2Writable.pm
@@ -243,6 +243,9 @@ 	}
 
 	if ($self->{parallel}) {
 		pipe(my ($r, $w)) or die "pipe failed: $!";
+		# pipe for barrier notifications doesn't need to be big,
+		# 1031: F_SETPIPE_SZ
+		fcntl($w, 1031, 4096) if $^O eq 'linux';
 		$self->{bnote} = [ $r, $w ];
 		$w->autoflush(1);
 	}