Re: svn commit: r206497 - in head: sbin/geom/class sbin/geom/class/sched sys/geom/sched sys/modules/geom sys/modules/geom/geom_sched sys/modules/geom/geom_sched/gs_sched sys/modules/geom/geom_sched/gs
tiny patch to fix a typo in the gsched(8) manual. ;) -- Alexander Best Index: sbin/geom/class/sched/gsched.8 === --- sbin/geom/class/sched/gsched.8 (revision 207154) +++ sbin/geom/class/sched/gsched.8 (working copy) @@ -93,8 +93,8 @@ on an already existing provider. .Pp A subsequent 'destroy' will remove the newly created geom and -hook the provider back to the original geom. -.Ar algorithm +hook the provider back to the original geom +.Ar algorithm . .It Cm configure Configure existing scheduling provider. It supports the same options as the ___ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to svn-src-head-unsubscr...@freebsd.org
Re: svn commit: r206497 - in head: sbin/geom/class sbin/geom/class/sched sys/geom/sched sys/modules/geom sys/modules/geom/geom_sched sys/modules/geom/geom_sched/gs_sched sys/modules/geom/geom_sched/gs
On Monday 12 April 2010 17:37:45 Luigi Rizzo wrote: Author: luigi Date: Mon Apr 12 16:37:45 2010 New Revision: 206497 URL: http://svn.freebsd.org/changeset/base/206497 Log: Bring in geom_sched, support for scheduling disk I/O requests in a device independent manner. Also include an example anticipatory scheduler, gsched_rr, which gives very nice performance improvements in presence of competing random access patterns. The example in gsched(8) says to use -s rr, but it looks like it should be -a rr? -- Bruce Cran ___ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to svn-src-head-unsubscr...@freebsd.org
Re: svn commit: r206497 - in head: sbin/geom/class sbin/geom/class/sched sys/geom/sched sys/modules/geom sys/modules/geom/geom_sched sys/modules/geom/geom_sched/gs_sched sys/modules/geom/geom_sched/gs
On 04/12/2010 06:37 PM, Luigi Rizzo wrote: Bring in geom_sched, support for scheduling disk I/O requests in a device independent manner. Also include an example anticipatory scheduler, gsched_rr, which gives very nice performance improvements in presence of competing random access patterns. This is joint work with Fabio Checconi, developed last year and presented at BSDCan 2009. You can find details in the README file or at Are there any plans to bring in something like Linux's ionice (or even better solutions)? Is it possible to do it easily at all (the user and GEOM are seemingly very far from each other)? ___ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to svn-src-head-unsubscr...@freebsd.org
Re: svn commit: r206497 - in head: sbin/geom/class sbin/geom/class/sched sys/geom/sched sys/modules/geom sys/modules/geom/geom_sched sys/modules/geom/geom_sched/gs_sched sys/modules/geom/geom_sched/gs
On Thu, Apr 15, 2010 at 04:38:23PM +0200, Attila Nagy wrote: On 04/12/2010 06:37 PM, Luigi Rizzo wrote: Bring in geom_sched, support for scheduling disk I/O requests in a device independent manner. Also include an example anticipatory scheduler, gsched_rr, which gives very nice performance improvements in presence of competing random access patterns. This is joint work with Fabio Checconi, developed last year and presented at BSDCan 2009. You can find details in the README file or at Are there any plans to bring in something like Linux's ionice (or even better solutions)? Is it possible to do it easily at all (the user and GEOM are seemingly very far from each other)? I can easily[*] modify the I/O priority/weight of process or threads, but you have to keep in mind that once a request is intercepted by the filesystem code (e.g. for delayed writes, or avoid duplication of pending reads), by the time it hits the disk it is not trivial to tell who should be charged for it. This is an area where we still need to experiment a bit (especially to find on which process issues which request, say for metadata, delayed writes, shared reads). [*] the 'easy' way is put the information in an external hash table and look it up using as a search key either of uid, gid, pid/struct thread *. I think we did something like this in the GSOC2005 project on disk scheduling. A more intrusive way involves extending the struct thread with an extra field to store the io priority. cheers luigi ___ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to svn-src-head-unsubscr...@freebsd.org
Re: svn commit: r206497 - in head: sbin/geom/class sbin/geom/class/sched sys/geom/sched sys/modules/geom sys/modules/geom/geom_sched sys/modules/geom/geom_sched/gs_sched sys/modules/geom/geom_sched/gs
On Thu, 15.04.2010 at 17:15:57 +0200, Luigi Rizzo wrote: On Thu, Apr 15, 2010 at 04:38:23PM +0200, Attila Nagy wrote: On 04/12/2010 06:37 PM, Luigi Rizzo wrote: Bring in geom_sched, support for scheduling disk I/O requests in a device independent manner. Also include an example anticipatory scheduler, gsched_rr, which gives very nice performance improvements in presence of competing random access patterns. This is joint work with Fabio Checconi, developed last year and presented at BSDCan 2009. You can find details in the README file or at Are there any plans to bring in something like Linux's ionice (or even better solutions)? Is it possible to do it easily at all (the user and GEOM are seemingly very far from each other)? I can easily[*] modify the I/O priority/weight of process or threads, but you have to keep in mind that once a request is intercepted by the filesystem code (e.g. for delayed writes, or avoid duplication of pending reads), by the time it hits the disk it is not trivial to tell who should be charged for it. This is an area where we still need to experiment a bit (especially to find on which process issues which request, say for metadata, delayed writes, shared reads). [*] the 'easy' way is put the information in an external hash table and look it up using as a search key either of uid, gid, pid/struct thread *. I think we did something like this in the GSOC2005 project on disk scheduling. A more intrusive way involves extending the struct thread with an extra field to store the io priority. What would already be helpful, is an I/O time measurement of the overall system and have that displayed in, eg., vmstat like Linux and Solaris do. It gives a better measure of if a system is CPU bound or I/O bound or neither. Can the scheduler help here? Uli ___ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to svn-src-head-unsubscr...@freebsd.org
Re: svn commit: r206497 - in head: sbin/geom/class sbin/geom/class/sched sys/geom/sched sys/modules/geom sys/modules/geom/geom_sched sys/modules/geom/geom_sched/gs_sched sys/modules/geom/geom_sched/gs
On Mon, Apr 12, 2010 at 11:05:12PM +0200, Luigi Rizzo wrote:
On Mon, Apr 12, 2010 at 10:49:26PM +0200, Pawel Jakub Dawidek wrote:
...
@@ -0,0 +1,19 @@
+# GEOM_LIBRARY_PATH
+# $FreeBSD$
+
+.PATH: /usr/src/sbin/geom/misc
+
+CFLAGS += -I/usr/src/sbin/geom
This doesn't look right.
probably a leftover from older versions of this code for 6.x .
I will do more tests tomorrow (for 7.x at this point, there is
no point in trying to support 6.x I believe) and try to remove
it if not necessary.
As Rui said you should use ${.CURDIR} instead of hardcoding /usr/src/.
BTW. So you decided to implement insert/remove functionality after all.
I have some questions:
- It is implemented as internal gsched hack, which is a pity, because
this might be very useful functionality for other classes in the future.
Is there a plan to make it more general and move it to the GEOM itself?
- Why g_sched_flush_pending() operates on global structure? I think it
will break if you try to insert and remove at the same time.
--
Pawel Jakub Dawidek http://www.wheelsystems.com
p...@freebsd.org http://www.FreeBSD.org
FreeBSD committer Am I Evil? Yes, I Am!
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Re: svn commit: r206497 - in head: sbin/geom/class sbin/geom/class/sched sys/geom/sched sys/modules/geom sys/modules/geom/geom_sched sys/modules/geom/geom_sched/gs_sched sys/modules/geom/geom_sched/gs
On Wed, Apr 14, 2010 at 09:46:17AM +0200, Pawel Jakub Dawidek wrote: BTW. So you decided to implement insert/remove functionality after all. I have some questions: - It is implemented as internal gsched hack, which is a pity, because this might be very useful functionality for other classes in the future. Is there a plan to make it more general and move it to the GEOM itself? - Why g_sched_flush_pending() operates on global structure? I think it will break if you try to insert and remove at the same time. One more thing:) If I read code correctly, new provider has different name than the original one. If my userland tool send command to my class and my class tries to find provider by name by scaning existing geoms, it won't find it, because provider's name is different. Wouldn't it better to change old provider's name and use the name old provider had for new provider? Sounds hackish... Another thing that comes to my mind is possibility to create providers that are not represented in /dev/. Name collision wouldn't be a problem then. Also, it seems nicer to not polute /dev/ with such proxy-providers. -- Pawel Jakub Dawidek http://www.wheelsystems.com p...@freebsd.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! pgpUnuaFoXHiD.pgp Description: PGP signature
Re: svn commit: r206497 - in head: sbin/geom/class sbin/geom/class/sched sys/geom/sched sys/modules/geom sys/modules/geom/geom_sched sys/modules/geom/geom_sched/gs_sched sys/modules/geom/geom_sched/gs
[Cc-ing Fabio as he may have more details]
On Wed, Apr 14, 2010 at 09:46:17AM +0200, Pawel Jakub Dawidek wrote:
On Mon, Apr 12, 2010 at 11:05:12PM +0200, Luigi Rizzo wrote:
On Mon, Apr 12, 2010 at 10:49:26PM +0200, Pawel Jakub Dawidek wrote:
...
@@ -0,0 +1,19 @@
+# GEOM_LIBRARY_PATH
+# $FreeBSD$
+
+.PATH: /usr/src/sbin/geom/misc
+
+CFLAGS += -I/usr/src/sbin/geom
This doesn't look right.
probably a leftover from older versions of this code for 6.x .
I will do more tests tomorrow (for 7.x at this point, there is
no point in trying to support 6.x I believe) and try to remove
it if not necessary.
As Rui said you should use ${.CURDIR} instead of hardcoding /usr/src/.
I thought i already fixed this yesterday.
BTW. So you decided to implement insert/remove functionality after all.
I have some questions:
- It is implemented as internal gsched hack, which is a pity, because
this might be very useful functionality for other classes in the future.
Is there a plan to make it more general and move it to the GEOM itself?
yes there is such a plan -- of course if nobody has objections.
In principle it is only a library extensions with no modifications
to geom internals.
However, when we developed that last year, we hit some corner case
where removal of an active node causes either a race or (if you try
to protect from the race) a livelock. Fixing this may require some
small cleanup to geom internals (we discusses the issue with phk
at last EuroBSDCon. Fabio may give you more details, as far as i
remember the problem was that some geom code takes shortcuts instead
of following a chain of pointers, and this can end up in the wrong
place in case of a removal.)
For this reason, at this time i am not recommending to remove a
node from a chain with outstanding transactions until the issue is solved.
- Why g_sched_flush_pending() operates on global structure? I think it
will break if you try to insert and remove at the same time.
i need to check this.
cheers
luigi
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Re: svn commit: r206497 - in head: sbin/geom/class sbin/geom/class/sched sys/geom/sched sys/modules/geom sys/modules/geom/geom_sched sys/modules/geom/geom_sched/gs_sched sys/modules/geom/geom_sched/gs
From: Luigi Rizzo ri...@iet.unipi.it Date: Wed, Apr 14, 2010 10:16:30AM +0200 [Cc-ing Fabio as he may have more details] ... BTW. So you decided to implement insert/remove functionality after all. I have some questions: - It is implemented as internal gsched hack, which is a pity, because this might be very useful functionality for other classes in the future. Is there a plan to make it more general and move it to the GEOM itself? yes there is such a plan -- of course if nobody has objections. In principle it is only a library extensions with no modifications to geom internals. However, when we developed that last year, we hit some corner case where removal of an active node causes either a race or (if you try to protect from the race) a livelock. Fixing this may require some small cleanup to geom internals (we discusses the issue with phk at last EuroBSDCon. Fabio may give you more details, as far as i remember the problem was that some geom code takes shortcuts instead of following a chain of pointers, and this can end up in the wrong place in case of a removal.) For this reason, at this time i am not recommending to remove a node from a chain with outstanding transactions until the issue is solved. I'm not sure I remember all the details, the major issues were: - g_disk_done() dereferences bio-parent-bio_to-geom-softc, thus changing bio_to-geom on the fly was not possible with pending request (they would find a wrong softc when bubbling up). For this reason we added a loop in g_insert_proxy() to wait for all the pending requests to be completed prior to inserting the proxy; but: - g_slice_finish_hot() completes requests in the event handling path, thus said loop (executed from an event handler) could result in a deadlock. To avoid this (it should be far from being frequent, considering the usages of hotspots in the slice code) g_insert_proxy() fails if it takes too long to complete the old requests. - Some classes (from a quick look I've seen only g_mirror, but I'm pretty sure there were some other ones) cache pointers to their providers. With these classes this implementation does not work. For the scheduler this is not a big issue, because its natural position is as close as possible to the disk device, but makes the mechanism quite hard to use in a more generic context. - Why g_sched_flush_pending() operates on global structure? I think it will break if you try to insert and remove at the same time. If I'm not wrong, this should be safe because the global list is used only under critical sections protected by the topology lock. ___ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to svn-src-head-unsubscr...@freebsd.org
Re: svn commit: r206497 - in head: sbin/geom/class sbin/geom/class/sched sys/geom/sched sys/modules/geom sys/modules/geom/geom_sched sys/modules/geom/geom_sched/gs_sched sys/modules/geom/geom_sched/gs
On Wed, Apr 14, 2010 at 06:05:54PM +0200, Fabio Checconi wrote: - Some classes (from a quick look I've seen only g_mirror, but I'm pretty sure there were some other ones) cache pointers to their providers. With these classes this implementation does not work. This can be easly changed to go though geom to provider. Many of my classes do that. -- Pawel Jakub Dawidek http://www.wheelsystems.com p...@freebsd.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! pgp3alHfLY40r.pgp Description: PGP signature
Re: svn commit: r206497 - in head: sbin/geom/class sbin/geom/class/sched sys/geom/sched sys/modules/geom sys/modules/geom/geom_sched sys/modules/geom/geom_sched/gs_sched sys/modules/geom/geom_sched/gs
On Mon, Apr 12, 2010 at 04:37:45PM +, Luigi Rizzo wrote: Author: luigi Date: Mon Apr 12 16:37:45 2010 New Revision: 206497 URL: http://svn.freebsd.org/changeset/base/206497 Log: Bring in geom_sched, support for scheduling disk I/O requests in a device independent manner. Also include an example anticipatory scheduler, gsched_rr, which gives very nice performance improvements in presence of competing random access patterns. Nice work:) Added: head/sbin/geom/class/sched/Makefile == --- /dev/null 00:00:00 1970 (empty, because file is newly added) +++ head/sbin/geom/class/sched/Makefile Mon Apr 12 16:37:45 2010 (r206497) @@ -0,0 +1,19 @@ +# GEOM_LIBRARY_PATH +# $FreeBSD$ + +.PATH: /usr/src/sbin/geom/misc + +CFLAGS += -I/usr/src/sbin/geom This doesn't look right. -- Pawel Jakub Dawidek http://www.wheelsystems.com p...@freebsd.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! pgpGCuW9vn2LH.pgp Description: PGP signature
