From ae1a633131f26bf31e4d8cd0646c6f40f0f0aa2b Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Fri, 18 Jul 2025 01:39:42 +0000
Subject: [PATCH] psgi_rproxy: standardize on 64K I/O size

Much of our bulk I/O in DS and IO.pm already uses 64K buffers
(matching the Linux default pipe size) instead of 16K buffers.
While larger I/O sizes can result in more work for the malloc
implementation, they can also reduce syscall and Perl function
call overhead to reduce CPU usage and improve throughput on long
fat networks (LFNs).  Furthermore, standardizing on larger sizes
ought to reduce fragmentation since malloc can avoid splitting
existing buffers used for bulk I/O we do in other places.
---
 lib/PublicInbox/H1ReqRes.pm | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/lib/PublicInbox/H1ReqRes.pm b/lib/PublicInbox/H1ReqRes.pm
index bb68bcf3b..8f49b45b6 100644
--- a/lib/PublicInbox/H1ReqRes.pm
+++ b/lib/PublicInbox/H1ReqRes.pm
@@ -18,6 +18,7 @@ use constant { # duplicated from HTTP.pm
 	CHUNK_END => -2,     # \r\n
 	CHUNK_TLR_END => -3, # (trailers*)?\r\n
 	CHUNK_MAX_HDR => 256,
+	IO_SIZE => 1 << 16,
 };
 
 sub new {
@@ -176,7 +177,7 @@ sub pass_res_chunked ($) {
 					\n)* \r\n)//ismx) {
 				return pass_trailers $self, $1;
 			}
-			die 'chunk not terminated' if length($$rbuf) > 0x4000;
+			die 'chunk not terminated' if length($$rbuf) > IO_SIZE;
 		}
 		if ($len == CHUNK_END) {
 			if ($$rbuf =~ s/\A\r\n//s) {
@@ -196,7 +197,7 @@ sub pass_res_chunked ($) {
 			} # else break from loop since $len >= 0
 		}
 		if ($len < 0) {
-			pass_refill($self, 0x4000, \&pass_res_chunked, $len) or
+			pass_refill($self, IO_SIZE, \&pass_res_chunked, $len) or
 				return;
 			# (implicit) goto chunk_start if $r > 0;
 		}
@@ -216,7 +217,7 @@ sub pass_res_chunked ($) {
 			}
 			if ($$rbuf eq '') {
 				# read more of current chunk
-				pass_refill($self, 0x4000,
+				pass_refill($self, IO_SIZE,
 					\&pass_res_chunked, $len) or return;
 			}
 		}
@@ -232,7 +233,7 @@ sub pass_res_identity ($) {
 			$len = _pass_res_block($self, $len) // return;
 		}
 		if ($$rbuf eq '' && $len) {
-			my $n = $len > 0x4000 ? 0x4000 : $len;
+			my $n = $len > IO_SIZE ? IO_SIZE : $len;
 			pass_refill($self, $n, \&pass_res_identity, $len) or
 				return;
 		}
@@ -250,7 +251,7 @@ sub pass_res_until_eof ($) { # HTTP/1.0-only
 			$$rbuf = '';
 		}
 		if ($$rbuf eq '') {
-			my $r = pass_refill($self, 0x4000,
+			my $r = pass_refill($self, IO_SIZE,
 					\&pass_res_until_eof, undef) // return;
 			last if $r == 0; # done
 		}
@@ -262,7 +263,7 @@ sub pass_res_hdr ($) { # called by flush_write
 	my ($self) = @_;
 	my ($rbuf, $r, $code, $phdr);
 	$rbuf = $self->{rbuf} // do {
-		$self->do_read(\(my $buf = ''), 0x4000) or
+		$self->do_read(\(my $buf = ''), IO_SIZE) or
 			return read_err $self, \&pass_res_hdr;
 		$self->{rbuf} = \$buf;
 	};
@@ -273,7 +274,7 @@ sub pass_res_hdr ($) { # called by flush_write
 		if ($r == -2) { # incomplete
 			length($$rbuf) > 0x4000 and
 				die 'upstream response headers too large';
-			$self->do_read($rbuf, 8192, length($$rbuf)) or return
+			$self->do_read($rbuf, IO_SIZE, length($$rbuf)) or return
 				read_err $self, \&pass_res_hdr;
 		} else {
 			die "upstream sent bad response headers (r=$r)";
@@ -342,7 +343,7 @@ sub send_req_body { # called by flush_write
 	# n.b. PublicInbox::HTTP always reads the entire request body
 	# before dispatching the PSGI app
 	my $r = $self->{req_left};
-	$r = 0x4000 if $r > 0x4000;
+	$r = IO_SIZE if $r > IO_SIZE;
 	$r = $self->{env}->{'psgi.input'}->read(my $buf, $r) //
 			die "input->read: $! ($self->{req_left} bytes left)";
 	die "input->read: EOF ($self->{req_left} bytes left)" if $r == 0;
-- 
2.47.2