bwillwrite() is called in kern/sys_generic.c:dofilewrite()
bwillwrite() is meant as a quick stop before doing any vnode
ops to flush dirty buffers to prevent a deadlock.
However:
1) afaik only VNODES have backing buffers, so stalling socket/pipes
doesn't gain us anything
2) writev() doesn't call bwillwrite()
shouldn't the code be changed like so:
Index: sys_generic.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/sys_generic.c,v
retrieving revision 1.65
diff -u -r1.65 sys_generic.c
--- sys_generic.c 2000/11/21 20:22:34 1.65
+++ sys_generic.c 2000/11/27 07:18:48
@@ -403,7 +403,8 @@
}
#endif
cnt = nbyte;
- bwillwrite();
+ if (fp->f_type == DTYPE_VNODE)
+ bwillwrite();
if ((error = fo_write(fp, &auio, fp->f_cred, flags, p))) {
if (auio.uio_resid != cnt && (error == ERESTART ||
error == EINTR || error == EWOULDBLOCK))
@@ -495,6 +496,8 @@
}
#endif
cnt = auio.uio_resid;
+ if (fp->f_type == DTYPE_VNODE)
+ bwillwrite();
if ((error = fo_write(fp, &auio, fp->f_cred, 0, p))) {
if (auio.uio_resid != cnt && (error == ERESTART ||
error == EINTR || error == EWOULDBLOCK))
thanks,
--
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