nginx (1.1.19) socket-level configuration of tcp_nodelay
I'm curious about
https://github.com/nginx/nginx/blob/master/src/core/ngx_connection.c
Specifically, line 838 in ngx_configure_listening_sockets():
#if 0
if (1) {
int tcp_nodelay = 1;
if (setsockopt(ls[i].fd, IPPROTO_TCP, TCP_NODELAY,
(const void *) &tcp_nodelay, sizeof(int))
== -1) //old-the current code calls an internal function to do this
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_socket_errno,
"setsockopt(TCP_NODELAY) %V failed, ignored",
&ls[i].addr_text);
}
}
#endif
Using getsockopt, I was indeed able to determine that none of my accept sockets had TCP_NODELAY set. Removing the preprocessor block fixed this. But why is it there? If the intention is to configure the accepted socket later and explicitly, I can't figure out where this is happening.
This app builds full responses before calling send, so traditional wisdom would be to disable nagle(enable TCP_NODELAY), but *I figure there is either a correct way to enable TCP_NODELAY or nginx has a very good reason for not enabling it.*
Am I correct, and if so, which is it?
(for the record, this question mostly involves
c sockets nginx tcp
asked Nov 16 '18 at 20:30
zzxyz
2,1831624
add a comment |
I'm curious about
https://github.com/nginx/nginx/blob/master/src/core/ngx_connection.c
Specifically, line 838 in ngx_configure_listening_sockets():
#if 0
if (1) {
int tcp_nodelay = 1;
if (setsockopt(ls[i].fd, IPPROTO_TCP, TCP_NODELAY,
(const void *) &tcp_nodelay, sizeof(int))
== -1) //old-the current code calls an internal function to do this
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_socket_errno,
"setsockopt(TCP_NODELAY) %V failed, ignored",
&ls[i].addr_text);
}
}
#endif
Using getsockopt, I was indeed able to determine that none of my accept sockets had TCP_NODELAY set. Removing the preprocessor block fixed this. But why is it there? If the intention is to configure the accepted socket later and explicitly, I can't figure out where this is happening.
This app builds full responses before calling send, so traditional wisdom would be to disable nagle(enable TCP_NODELAY), but *I figure there is either a correct way to enable TCP_NODELAY or nginx has a very good reason for not enabling it.*
Am I correct, and if so, which is it?
(for the record, this question mostly involves
c sockets nginx tcp
asked Nov 16 '18 at 20:30
zzxyz
2,1831624
1
The code you show sets TCP_NODELAY on the listening socket - which may be inherited by the accept()'ed sockets - but that isn't portable. The same file has angx_tcp_nodelay()function to set TCP_NODELAY on the (non-listening) TCP sockets which are called from various places, depending on settings you have in nginx.conf
– nos
Nov 16 '18 at 20:37
@nos - I truly couldn't figure out from where. There was asendfiletype of socket where it was obvious, butnginxhas a 2-bit field in its internal structure for tcp_nodelay, and I really couldn't figure out anything consistent in how it was 1) set or 2) used. Not saying it's it not consistent. Just that if it is, I couldn't figure it out.
– zzxyz
Nov 16 '18 at 20:43
run e.ggrep -r ngx_tcp_nodelay( .to see where it's called from.
– nos
Nov 16 '18 at 20:44
@nos - Ah yes...It's clear what to do in the new nginx. My version doesn't have that function, the file that calls it, or the setting that file reads. You've answered the important part of my question for me, which is that they probably#ifdefedthat out for portability reasons (vs a deliberate attempt to enable nagle regardless of config). Thank you.
– zzxyz
Nov 16 '18 at 20:55
the relevant file (for the socket type in question) that calls it, I should say
– zzxyz
Nov 16 '18 at 21:05
add a comment |
I'm curious about
https://github.com/nginx/nginx/blob/master/src/core/ngx_connection.c
Specifically, line 838 in ngx_configure_listening_sockets():
#if 0
if (1) {
int tcp_nodelay = 1;
if (setsockopt(ls[i].fd, IPPROTO_TCP, TCP_NODELAY,
(const void *) &tcp_nodelay, sizeof(int))
== -1) //old-the current code calls an internal function to do this
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_socket_errno,
"setsockopt(TCP_NODELAY) %V failed, ignored",
&ls[i].addr_text);
}
}
#endif
Using getsockopt, I was indeed able to determine that none of my accept sockets had TCP_NODELAY set. Removing the preprocessor block fixed this. But why is it there? If the intention is to configure the accepted socket later and explicitly, I can't figure out where this is happening.
This app builds full responses before calling send, so traditional wisdom would be to disable nagle(enable TCP_NODELAY), but *I figure there is either a correct way to enable TCP_NODELAY or nginx has a very good reason for not enabling it.*
Am I correct, and if so, which is it?
(for the record, this question mostly involves
c sockets nginx tcp
asked Nov 16 '18 at 20:30
zzxyz
2,1831624
I'm curious about
https://github.com/nginx/nginx/blob/master/src/core/ngx_connection.c
Specifically, line 838 in ngx_configure_listening_sockets():
#if 0
if (1) {
int tcp_nodelay = 1;
if (setsockopt(ls[i].fd, IPPROTO_TCP, TCP_NODELAY,
(const void *) &tcp_nodelay, sizeof(int))
== -1) //old-the current code calls an internal function to do this
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_socket_errno,
"setsockopt(TCP_NODELAY) %V failed, ignored",
&ls[i].addr_text);
}
}
#endif
Using getsockopt, I was indeed able to determine that none of my accept sockets had TCP_NODELAY set. Removing the preprocessor block fixed this. But why is it there? If the intention is to configure the accepted socket later and explicitly, I can't figure out where this is happening.
This app builds full responses before calling send, so traditional wisdom would be to disable nagle(enable TCP_NODELAY), but *I figure there is either a correct way to enable TCP_NODELAY or nginx has a very good reason for not enabling it.*
Am I correct, and if so, which is it?
(for the record, this question mostly involves
c sockets nginx tcp
c sockets nginx tcp
asked Nov 16 '18 at 20:30
zzxyz
2,1831624
asked Nov 16 '18 at 20:30
zzxyz
2,1831624
edited Nov 17 '18 at 0:52
asked Nov 16 '18 at 20:30
zzxyz
2,1831624
asked Nov 16 '18 at 20:30
zzxyz
2,1831624
asked Nov 16 '18 at 20:30
zzxyz
2,1831624
2,1831624
1
The code you show sets TCP_NODELAY on the listening socket - which may be inherited by the accept()'ed sockets - but that isn't portable. The same file has angx_tcp_nodelay()function to set TCP_NODELAY on the (non-listening) TCP sockets which are called from various places, depending on settings you have in nginx.conf
– nos
Nov 16 '18 at 20:37
@nos - I truly couldn't figure out from where. There was asendfiletype of socket where it was obvious, butnginxhas a 2-bit field in its internal structure for tcp_nodelay, and I really couldn't figure out anything consistent in how it was 1) set or 2) used. Not saying it's it not consistent. Just that if it is, I couldn't figure it out.
– zzxyz
Nov 16 '18 at 20:43
run e.ggrep -r ngx_tcp_nodelay( .to see where it's called from.
– nos
Nov 16 '18 at 20:44
@nos - Ah yes...It's clear what to do in the new nginx. My version doesn't have that function, the file that calls it, or the setting that file reads. You've answered the important part of my question for me, which is that they probably#ifdefedthat out for portability reasons (vs a deliberate attempt to enable nagle regardless of config). Thank you.
– zzxyz
Nov 16 '18 at 20:55
the relevant file (for the socket type in question) that calls it, I should say
– zzxyz
Nov 16 '18 at 21:05
add a comment |
1
The code you show sets TCP_NODELAY on the listening socket - which may be inherited by the accept()'ed sockets - but that isn't portable. The same file has angx_tcp_nodelay()function to set TCP_NODELAY on the (non-listening) TCP sockets which are called from various places, depending on settings you have in nginx.conf
– nos
Nov 16 '18 at 20:37
@nos - I truly couldn't figure out from where. There was asendfiletype of socket where it was obvious, butnginxhas a 2-bit field in its internal structure for tcp_nodelay, and I really couldn't figure out anything consistent in how it was 1) set or 2) used. Not saying it's it not consistent. Just that if it is, I couldn't figure it out.
– zzxyz
Nov 16 '18 at 20:43
run e.ggrep -r ngx_tcp_nodelay( .to see where it's called from.
– nos
Nov 16 '18 at 20:44
@nos - Ah yes...It's clear what to do in the new nginx. My version doesn't have that function, the file that calls it, or the setting that file reads. You've answered the important part of my question for me, which is that they probably#ifdefedthat out for portability reasons (vs a deliberate attempt to enable nagle regardless of config). Thank you.
– zzxyz
Nov 16 '18 at 20:55
the relevant file (for the socket type in question) that calls it, I should say
– zzxyz
Nov 16 '18 at 21:05
1
1
The code you show sets TCP_NODELAY on the listening socket - which may be inherited by the accept()'ed sockets - but that isn't portable. The same file has a
ngx_tcp_nodelay() function to set TCP_NODELAY on the (non-listening) TCP sockets which are called from various places, depending on settings you have in nginx.conf– nos
Nov 16 '18 at 20:37
The code you show sets TCP_NODELAY on the listening socket - which may be inherited by the accept()'ed sockets - but that isn't portable. The same file has a
ngx_tcp_nodelay() function to set TCP_NODELAY on the (non-listening) TCP sockets which are called from various places, depending on settings you have in nginx.conf– nos
Nov 16 '18 at 20:37
@nos - I truly couldn't figure out from where. There was a
sendfile type of socket where it was obvious, but nginx has a 2-bit field in its internal structure for tcp_nodelay, and I really couldn't figure out anything consistent in how it was 1) set or 2) used. Not saying it's it not consistent. Just that if it is, I couldn't figure it out.– zzxyz
Nov 16 '18 at 20:43
@nos - I truly couldn't figure out from where. There was a
sendfile type of socket where it was obvious, but nginx has a 2-bit field in its internal structure for tcp_nodelay, and I really couldn't figure out anything consistent in how it was 1) set or 2) used. Not saying it's it not consistent. Just that if it is, I couldn't figure it out.– zzxyz
Nov 16 '18 at 20:43
run e.g
grep -r ngx_tcp_nodelay( . to see where it's called from.– nos
Nov 16 '18 at 20:44
run e.g
grep -r ngx_tcp_nodelay( . to see where it's called from.– nos
Nov 16 '18 at 20:44
@nos - Ah yes...It's clear what to do in the new nginx. My version doesn't have that function, the file that calls it, or the setting that file reads. You've answered the important part of my question for me, which is that they probably
#ifdefed that out for portability reasons (vs a deliberate attempt to enable nagle regardless of config). Thank you.– zzxyz
Nov 16 '18 at 20:55
@nos - Ah yes...It's clear what to do in the new nginx. My version doesn't have that function, the file that calls it, or the setting that file reads. You've answered the important part of my question for me, which is that they probably
#ifdefed that out for portability reasons (vs a deliberate attempt to enable nagle regardless of config). Thank you.– zzxyz
Nov 16 '18 at 20:55
the relevant file (for the socket type in question) that calls it, I should say
– zzxyz
Nov 16 '18 at 21:05
the relevant file (for the socket type in question) that calls it, I should say
– zzxyz
Nov 16 '18 at 21:05
add a comment |
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1
The code you show sets TCP_NODELAY on the listening socket - which may be inherited by the accept()'ed sockets - but that isn't portable. The same file has a
ngx_tcp_nodelay()function to set TCP_NODELAY on the (non-listening) TCP sockets which are called from various places, depending on settings you have in nginx.conf– nos
Nov 16 '18 at 20:37
@nos - I truly couldn't figure out from where. There was a
sendfiletype of socket where it was obvious, butnginxhas a 2-bit field in its internal structure for tcp_nodelay, and I really couldn't figure out anything consistent in how it was 1) set or 2) used. Not saying it's it not consistent. Just that if it is, I couldn't figure it out.– zzxyz
Nov 16 '18 at 20:43
run e.g
grep -r ngx_tcp_nodelay( .to see where it's called from.– nos
Nov 16 '18 at 20:44
@nos - Ah yes...It's clear what to do in the new nginx. My version doesn't have that function, the file that calls it, or the setting that file reads. You've answered the important part of my question for me, which is that they probably
#ifdefedthat out for portability reasons (vs a deliberate attempt to enable nagle regardless of config). Thank you.– zzxyz
Nov 16 '18 at 20:55
the relevant file (for the socket type in question) that calls it, I should say
– zzxyz
Nov 16 '18 at 21:05