On Wed, Jun 18, 2003 at 11:25:36PM +0200, Poul-Henning Kamp wrote:
>
> I have uploaded a proof of concept patch:
>
> http://phk.freebsd.dk/patch/fd_dev.patch
>
>
> WARNING: It is perfectly possibly that this patch eats your machine
> WARNING: destroys your disk and makes your corn-flakes soggy.
> WARNING: RUN AT YOUR OWN RISK!
>
>
> This patch basically shortcuts access from userland to devices
> directly from the file descriptor level through DEVFS to the device
> driver.
>
> So far there are no indications that we will not be moving in this
> direction pretty soon, but it may not be this exact way we do it,
> this is only a proof of concept at this point.
>
> I have only tested this patch lightly on a disk-less machine, I
> have not tried a lot of advanced stuff with it, and I have already
> noticed that syslogd seems to have an issue with it during startup
> (I just press ctrl-C for now).
>
> The patch is controlled by the sysctl "debug.phk" which can take
> the values 0 (disabled) or 1 (enabled).
>
> But the good news is that there is a measurable performance improvement:
>
> syv# sysctl debug.phk=0
> debug.phk: 1 -> 0
> syv# dd if=/dev/zero of=/dev/null count=100000
> 100000+0 records in
> 100000+0 records out
> 51200000 bytes transferred in 4.784862 secs (10700413 bytes/sec)
> syv# sysctl debug.phk=1
> debug.phk: 0 -> 1
> syv# dd if=/dev/zero of=/dev/null count=100000
> 100000+0 records in
> 100000+0 records out
> 51200000 bytes transferred in 2.211927 secs (23147238 bytes/sec)
>
> And with this code enabled, it is possible to go from userland to
> device driver without touching Giant underway.
>
> Comments and test-results are most welcome!
Hmm...
diff -u -r1.61 file.h
--- sys/file.h 18 Jun 2003 19:53:59 -0000 1.61
+++ sys/file.h 18 Jun 2003 20:44:48 -0000
@@ -62,6 +62,7 @@
#define DTYPE_FIFO 4 /* fifo (named pipe) */
#define DTYPE_KQUEUE 5 /* event queue */
#define DTYPE_CRYPTO 6 /* crypto */
+#define DTYPE_DEVICE 7 /* crypto */
^^^^^^
looks like comment wrong, isn't it?
--
Rgdz, /"\ ASCII RIBBON CAMPAIGN
Sergey Osokin aka oZZ, \ / AGAINST HTML MAIL
http://ozz.pp.ru/ X AND NEWS
/ \
_______________________________________________
[EMAIL PROTECTED] mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-current
To unsubscribe, send any mail to "[EMAIL PROTECTED]"
