From 01b6a164d94f26be7ad500f71210bdb888f416aa Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Sun, 16 Feb 2025 08:31:13 +0100 Subject: tcp_splice: A typo three years ago and SO_RCVLOWAT is gone In commit e5eefe77435a ("tcp: Refactor to use events instead of states, split out spliced implementation"), this: if (!bitmap_isset(rcvlowat_set, conn - ts) && readlen > (long)c->tcp.pipe_size / 10) { (note the !) became: if (conn->flags & lowat_set_flag && readlen > (long)c->tcp.pipe_size / 10) { in the new tcp_splice_sock_handler(). We want to check, there, if we should set SO_RCVLOWAT, only if we haven't set it already. But, instead, we're checking if it's already set before we set it, so we'll never set it, of course. Fix the check and re-enable the functionality, which should give us improved CPU utilisation in non-interactive cases where we are not transferring at full pipe capacity. Fixes: e5eefe77435a ("tcp: Refactor to use events instead of states, split out spliced implementation") Reviewed-by: David Gibson Signed-off-by: Stefano Brivio --- tcp_splice.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tcp_splice.c b/tcp_splice.c index 8a39a6f..5d845c9 100644 --- a/tcp_splice.c +++ b/tcp_splice.c @@ -556,7 +556,7 @@ eintr: if (readlen >= (long)c->tcp.pipe_size * 10 / 100) continue; - if (conn->flags & lowat_set_flag && + if (!(conn->flags & lowat_set_flag) && readlen > (long)c->tcp.pipe_size / 10) { int lowat = c->tcp.pipe_size / 4; -- cgit v1.2.3