Closed
Description
by shawnlandden:
sendfile() is backed by splice() which can do arbitrary bidirectional IO between a
limited set of fd types, including TCP UDP files AF_ALG, etc (anything with a sendpage()
handler in the kernel)
the following application connects two tcp sockets, which sendfile() supports, but the
go runtime does not use sendfile()
this patch doesn't work, and i'm not sure why, i'm being held up by 6776
diff -r c4b7c0824984 src/pkg/net/sendfile_linux.go
--- a/src/pkg/net/sendfile_linux.go Fri Dec 20 23:19:32 2013 -0800
+++ b/src/pkg/net/sendfile_linux.go Sun Dec 22 15:42:18 2013 -0800
@@ -8,6 +8,8 @@
"io"
"os"
"syscall"
+ "reflect"
+ "fmt"
)
// maxSendfileSize is the largest chunk size we ask the kernel to copy
@@ -31,9 +33,17 @@
return 0, nil, true
}
}
+ fmt.Println(reflect.TypeOf(r))
f, ok := r.(*os.File)
+ var src int
if !ok {
- return 0, nil, false
+ t, ok := r.(*TCPConn)
+ if !ok {
+ return 0, nil, false
+ }
+ src = t.conn.fd.sysfd
+ } else {
+ src = int(f.Fd())
}
if err := c.writeLock(); err != nil {
@@ -42,7 +52,6 @@
defer c.writeUnlock()
dst := c.sysfd
- src := int(f.Fd())
for remain > 0 {
n := maxSendfileSize
if int64(n) > remain {
What steps will reproduce the problem?
If possible, include a link to a program on play.golang.org.
1.run http://play.golang.org/p/EvOJBw-Esm in strace
2. uses read/write when sendfile() possible
Which compiler are you using (5g, 6g, 8g, gccgo)?
6g. gccgo create a program that crashes (debian sid)
Which operating system are you using?
debian sid
Which version are you using? (run 'go version')
go version go1.2 linux/amd64
Please provide any additional information below.