For 32-bit machines rollback the default number of vnode pager pbufs
back to the lever before r343030. For 64-bit machines reduce it slightly, too. Together with r343030 I bumped the limit up to the value we use at Netflix to serve 100 Gbit/s of sendfile traffic, and it probably isn't a good default. Provide a loader tunable to change vnode pager pbufs count. Document it.
This commit is contained in:
parent
3c324b9465
commit
66fb0b1ad7
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=344188
@ -25,7 +25,7 @@
|
||||
.\"
|
||||
.\" $FreeBSD$
|
||||
.\"
|
||||
.Dd January 25, 2019
|
||||
.Dd February 15, 2019
|
||||
.Dt SENDFILE 2
|
||||
.Os
|
||||
.Sh NAME
|
||||
@ -48,6 +48,7 @@ The
|
||||
system call
|
||||
sends a regular file or shared memory object specified by descriptor
|
||||
.Fa fd
|
||||
h
|
||||
out a stream socket specified by descriptor
|
||||
.Fa s .
|
||||
.Pp
|
||||
@ -224,6 +225,19 @@ implementation of
|
||||
.Fn sendfile
|
||||
is "zero-copy", meaning that it has been optimized so that copying of the file data is avoided.
|
||||
.Sh TUNING
|
||||
.Ss physical paging buffers
|
||||
.Fn sendfile
|
||||
uses vnode pager to read file pages into memory.
|
||||
The pager uses a pool of physical buffers to run its I/O operations.
|
||||
When system runs out of pbufs, sendfile will block and report state
|
||||
.Dq Li zonelimit .
|
||||
Size of the pool can be tuned with
|
||||
.Va vm.vnode_pbufs
|
||||
.Xr loader.conf 5
|
||||
tunable and can be checked with
|
||||
.Xr sysctl 8
|
||||
OID of the same name at runtime.
|
||||
.Ss sendfile(2) buffers
|
||||
On some architectures, this system call internally uses a special
|
||||
.Fn sendfile
|
||||
buffer
|
||||
@ -279,9 +293,11 @@ buffers usage respectively.
|
||||
These values may also be viewed through
|
||||
.Nm netstat Fl m .
|
||||
.Pp
|
||||
If a value of zero is reported for
|
||||
.Va kern.ipc.nsfbufs ,
|
||||
your architecture does not need to use
|
||||
If
|
||||
.Xr sysctl 8
|
||||
OID
|
||||
.Va kern.ipc.nsfbufs
|
||||
doesn't exist, your architecture does not need to use
|
||||
.Fn sendfile
|
||||
buffers because their task can be efficiently performed
|
||||
by the generic virtual memory structures.
|
||||
@ -363,11 +379,13 @@ does not support
|
||||
The socket peer has closed the connection.
|
||||
.El
|
||||
.Sh SEE ALSO
|
||||
.Xr loader.conf 5 ,
|
||||
.Xr netstat 1 ,
|
||||
.Xr open 2 ,
|
||||
.Xr send 2 ,
|
||||
.Xr socket 2 ,
|
||||
.Xr writev 2 ,
|
||||
.Xr sysctl 8 ,
|
||||
.Xr tuning 7
|
||||
.Rs
|
||||
.%A K. Elmeleegy
|
||||
|
@ -115,13 +115,23 @@ SYSCTL_PROC(_debug, OID_AUTO, vnode_domainset, CTLTYPE_STRING | CTLFLAG_RW,
|
||||
&vnode_domainset, 0, sysctl_handle_domainset, "A",
|
||||
"Default vnode NUMA policy");
|
||||
|
||||
static int nvnpbufs;
|
||||
SYSCTL_INT(_vm, OID_AUTO, vnode_pbufs, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
|
||||
&nvnpbufs, 0, "number of physical buffers allocated for vnode pager");
|
||||
|
||||
static uma_zone_t vnode_pbuf_zone;
|
||||
|
||||
static void
|
||||
vnode_pager_init(void *dummy)
|
||||
{
|
||||
|
||||
vnode_pbuf_zone = pbuf_zsecond_create("vnpbuf", nswbuf * 8);
|
||||
#ifdef __LP64__
|
||||
nvnpbufs = nswbuf * 2;
|
||||
#else
|
||||
nvnpbufs = nswbuf / 2;
|
||||
#endif
|
||||
TUNABLE_INT_FETCH("vm.vnode_pbufs", &nvnpbufs);
|
||||
vnode_pbuf_zone = pbuf_zsecond_create("vnpbuf", nvnpbufs);
|
||||
}
|
||||
SYSINIT(vnode_pager, SI_SUB_CPU, SI_ORDER_ANY, vnode_pager_init, NULL);
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user