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Add the SF_NODISKIO flag to sendfile. This flag causes sendfile to be

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mindful of blocking on disk I/O and instead return EBUSY when such
blocking would occur.

Results from the DeBox project indicate that blocking on disk I/O
can slow the performance of a kqueue/poll based webserver.  Using
a flag such as SF_NODISKIO and throwing connections that would block
to helper processes/threads helped increase performance.

Currently, only the Flash webserver uses this flag, although it could
probably be applied to thttpd with relative ease.

Idea by:	Yaoping Ruan & Vivek Pai
This commit is contained in:
Mike Silbersack 2004-02-08 07:35:48 +00:00
parent 08fc808d7f
commit b49d824e8b
2 changed files with 27 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
sys/kern/uipc_syscalls.c
View File

@ -1836,7 +1836,11 @@ retry_lookup:
* If page is not valid for what we need, initiate I/O
*/
if (!pg->valid || !vm_page_is_valid(pg, pgoff, xfsize)) {
if (pg->valid && vm_page_is_valid(pg, pgoff, xfsize)) {
VM_OBJECT_UNLOCK(obj);
} else if (uap->flags & SF_NODISKIO) {
error = EBUSY;
} else {
int bsize, resid;
/*
@ -1867,26 +1871,25 @@ retry_lookup:
vm_page_lock_queues();
vm_page_flag_clear(pg, PG_ZERO);
vm_page_io_finish(pg);
if (error) {
vm_page_unwire(pg, 0);
/*
* See if anyone else might know about this page.
* If not and it is not valid, then free it.
*/
if (pg->wire_count == 0 && pg->valid == 0 &&
pg->busy == 0 && !(pg->flags & PG_BUSY) &&
pg->hold_count == 0) {
vm_page_busy(pg);
vm_page_free(pg);
}
vm_page_unlock_queues();
VM_OBJECT_UNLOCK(obj);
sbunlock(&so->so_snd);
goto done;
}
mbstat.sf_iocnt++;
} else {
}
if (error) {
vm_page_unwire(pg, 0);
/*
* See if anyone else might know about this page.
* If not and it is not valid, then free it.
*/
if (pg->wire_count == 0 && pg->valid == 0 &&
pg->busy == 0 && !(pg->flags & PG_BUSY) &&
pg->hold_count == 0) {
vm_page_busy(pg);
vm_page_free(pg);
}
vm_page_unlock_queues();
VM_OBJECT_UNLOCK(obj);
sbunlock(&so->so_snd);
goto done;
}
vm_page_unlock_queues();

5
sys/sys/socket.h
View File

@ -505,6 +505,11 @@ struct sf_hdtr {
struct iovec *trailers; /* pointer to an array of trailer struct iovec's */
int trl_cnt; /* number of trailer iovec's */
};
/*
* Sendfile-specific flag(s)
*/
#define SF_NODISKIO 0x00000001
#endif
#ifndef _KERNEL