git: b21104487324 - main - sendfile: ensure that the low water mark is at least a page size

The branch main has been updated by glebius:

URL: https://cgit.FreeBSD.org/src/commit/?id=b2110448732434841fc30bb0af0d28902a6621b3

commit b2110448732434841fc30bb0af0d28902a6621b3
Author:     Jonathan T. Looney <jtl@FreeBSD.org>
AuthorDate: 2025-04-30 17:03:04 +0000
Commit:     Gleb Smirnoff <glebius@FreeBSD.org>
CommitDate: 2025-04-30 17:05:47 +0000

    sendfile: ensure that the low water mark is at least a page size
    
    , when possible, to cut down on the possibility of short I/Os.
    
    This change has been at Netflix for several years already.
---
 sys/kern/kern_sendfile.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sys/kern/kern_sendfile.c b/sys/kern/kern_sendfile.c
index 05a820fe5ac1..d409f41824ad 100644
--- a/sys/kern/kern_sendfile.c
+++ b/sys/kern/kern_sendfile.c
@@ -779,6 +779,9 @@ vn_sendfile(struct file *fp, int sockfd, struct uio *hdr_uio,
 		SOCKBUF_LOCK(&so->so_snd);
 		if (so->so_snd.sb_lowat < so->so_snd.sb_hiwat / 2)
 			so->so_snd.sb_lowat = so->so_snd.sb_hiwat / 2;
+		if (so->so_snd.sb_lowat < PAGE_SIZE &&
+		    so->so_snd.sb_hiwat >= PAGE_SIZE)
+			so->so_snd.sb_lowat = PAGE_SIZE;
 retry_space:
 		if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
 			error = EPIPE;