Re: [RFC 5/5] pm: remove kernel thread freezing

On Wed, Oct 04, 2017 at 01:03:54AM +, Bart Van Assche wrote: > On Wed, 2017-10-04 at 02:47 +0200, Luis R. Rodriguez wrote: > > 3) Lookup for kthreads which seem to generate IO -- address / review if > > removal of the freezer API can be done somehow with a quescing. This > > is

Re: [RFC 5/5] pm: remove kernel thread freezing

On Wed, Oct 04, 2017 at 01:03:54AM +, Bart Van Assche wrote: > On Wed, 2017-10-04 at 02:47 +0200, Luis R. Rodriguez wrote: > > 3) Lookup for kthreads which seem to generate IO -- address / review if > > removal of the freezer API can be done somehow with a quescing. This > > is

Re: [RFC 5/5] pm: remove kernel thread freezing

On Fri, Oct 06, 2017 at 02:07:13PM +0200, Pavel Machek wrote: > > Yeah, I was not careful enough reading cover letter. Having series > where 1-4/5 are ready to go, and 5/5 not-good-idea for years to come > is quite confusing. 4/5 is not ready to go either, at the very least

Re: [RFC 5/5] pm: remove kernel thread freezing

On Fri, Oct 06, 2017 at 02:07:13PM +0200, Pavel Machek wrote: > > Yeah, I was not careful enough reading cover letter. Having series > where 1-4/5 are ready to go, and 5/5 not-good-idea for years to come > is quite confusing. 4/5 is not ready to go either, at the very least

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue 2017-10-03 22:49:40, Luis R. Rodriguez wrote: > On Tue, Oct 03, 2017 at 10:12:04PM +0200, Pavel Machek wrote: > > On Tue 2017-10-03 11:53:13, Luis R. Rodriguez wrote: > > > Now that all filesystems which used to rely on kthread > > > freezing have been converted to filesystem freeze/thawing

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue 2017-10-03 22:49:40, Luis R. Rodriguez wrote: > On Tue, Oct 03, 2017 at 10:12:04PM +0200, Pavel Machek wrote: > > On Tue 2017-10-03 11:53:13, Luis R. Rodriguez wrote: > > > Now that all filesystems which used to rely on kthread > > > freezing have been converted to filesystem freeze/thawing

Re: [RFC 5/5] pm: remove kernel thread freezing

On Wed, Oct 04, 2017 at 02:47:56AM +0200, Luis R. Rodriguez wrote: > On Tue, Oct 03, 2017 at 11:15:07PM +0200, Rafael J. Wysocki wrote: > > On Tuesday, October 3, 2017 8:59:00 PM CEST Rafael J. Wysocki wrote: > > > On Tuesday, October 3, 2017 8:53:13 PM CEST Luis R. Rodriguez wrote: > > > > Now

Re: [RFC 5/5] pm: remove kernel thread freezing

On Wed, Oct 04, 2017 at 02:47:56AM +0200, Luis R. Rodriguez wrote: > On Tue, Oct 03, 2017 at 11:15:07PM +0200, Rafael J. Wysocki wrote: > > On Tuesday, October 3, 2017 8:59:00 PM CEST Rafael J. Wysocki wrote: > > > On Tuesday, October 3, 2017 8:53:13 PM CEST Luis R. Rodriguez wrote: > > > > Now

Re: [RFC 5/5] pm: remove kernel thread freezing

On 10/03/2017 08:53 PM, Luis R. Rodriguez wrote: > Now that all filesystems which used to rely on kthread > freezing have been converted to filesystem freeze/thawing > we can remove the kernel kthread freezer. > > Signed-off-by: Luis R. Rodriguez > --- >

Re: [RFC 5/5] pm: remove kernel thread freezing

On 10/03/2017 08:53 PM, Luis R. Rodriguez wrote: > Now that all filesystems which used to rely on kthread > freezing have been converted to filesystem freeze/thawing > we can remove the kernel kthread freezer. > > Signed-off-by: Luis R. Rodriguez > --- >

Re: [RFC 5/5] pm: remove kernel thread freezing

On Wed, 2017-10-04 at 02:47 +0200, Luis R. Rodriguez wrote: > 3) Lookup for kthreads which seem to generate IO -- address / review if > removal of the freezer API can be done somehow with a quescing. This > is currently for example being done on SCSI / md. > 4) Only after all the

Re: [RFC 5/5] pm: remove kernel thread freezing

On Wed, 2017-10-04 at 02:47 +0200, Luis R. Rodriguez wrote: > 3) Lookup for kthreads which seem to generate IO -- address / review if > removal of the freezer API can be done somehow with a quescing. This > is currently for example being done on SCSI / md. > 4) Only after all the

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, Oct 03, 2017 at 11:15:07PM +0200, Rafael J. Wysocki wrote: > On Tuesday, October 3, 2017 8:59:00 PM CEST Rafael J. Wysocki wrote: > > On Tuesday, October 3, 2017 8:53:13 PM CEST Luis R. Rodriguez wrote: > > > Now that all filesystems which used to rely on kthread > > > freezing have been

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, Oct 03, 2017 at 11:15:07PM +0200, Rafael J. Wysocki wrote: > On Tuesday, October 3, 2017 8:59:00 PM CEST Rafael J. Wysocki wrote: > > On Tuesday, October 3, 2017 8:53:13 PM CEST Luis R. Rodriguez wrote: > > > Now that all filesystems which used to rely on kthread > > > freezing have been

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tuesday, October 3, 2017 8:59:00 PM CEST Rafael J. Wysocki wrote: > On Tuesday, October 3, 2017 8:53:13 PM CEST Luis R. Rodriguez wrote: > > Now that all filesystems which used to rely on kthread > > freezing have been converted to filesystem freeze/thawing > > we can remove the kernel kthread

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tuesday, October 3, 2017 8:59:00 PM CEST Rafael J. Wysocki wrote: > On Tuesday, October 3, 2017 8:53:13 PM CEST Luis R. Rodriguez wrote: > > Now that all filesystems which used to rely on kthread > > freezing have been converted to filesystem freeze/thawing > > we can remove the kernel kthread

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, Oct 03, 2017 at 03:09:53PM -0600, Shuah Khan wrote: > On Tue, Oct 3, 2017 at 3:00 PM, Jiri Kosina wrote: > > On Tue, 3 Oct 2017, Pavel Machek wrote: > > > >> > Again, I agree that the (rare) kthreads that are actually "creating" new > >> > I/O have to be somehow frozen

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, Oct 03, 2017 at 03:09:53PM -0600, Shuah Khan wrote: > On Tue, Oct 3, 2017 at 3:00 PM, Jiri Kosina wrote: > > On Tue, 3 Oct 2017, Pavel Machek wrote: > > > >> > Again, I agree that the (rare) kthreads that are actually "creating" new > >> > I/O have to be somehow frozen and require special

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, Oct 3, 2017 at 3:00 PM, Jiri Kosina wrote: > On Tue, 3 Oct 2017, Pavel Machek wrote: > >> > Again, I agree that the (rare) kthreads that are actually "creating" new >> > I/O have to be somehow frozen and require special care. >> >> Agreed. Was any effort made to identify

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, Oct 3, 2017 at 3:00 PM, Jiri Kosina wrote: > On Tue, 3 Oct 2017, Pavel Machek wrote: > >> > Again, I agree that the (rare) kthreads that are actually "creating" new >> > I/O have to be somehow frozen and require special care. >> >> Agreed. Was any effort made to identify those special

Re: [RFC 5/5] pm: remove kernel thread freezing

On Wed, Oct 04, 2017 at 08:04:49AM +1100, Dave Chinner wrote: > On Tue, Oct 03, 2017 at 11:53:13AM -0700, Luis R. Rodriguez wrote: > > Now that all filesystems which used to rely on kthread > > freezing have been converted to filesystem freeze/thawing > > we can remove the kernel kthread freezer.

Re: [RFC 5/5] pm: remove kernel thread freezing

On Wed, Oct 04, 2017 at 08:04:49AM +1100, Dave Chinner wrote: > On Tue, Oct 03, 2017 at 11:53:13AM -0700, Luis R. Rodriguez wrote: > > Now that all filesystems which used to rely on kthread > > freezing have been converted to filesystem freeze/thawing > > we can remove the kernel kthread freezer.

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, Oct 03, 2017 at 11:53:13AM -0700, Luis R. Rodriguez wrote: > Now that all filesystems which used to rely on kthread > freezing have been converted to filesystem freeze/thawing > we can remove the kernel kthread freezer. Really? There's no other subsystem that relies on kernel thread and

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, Oct 03, 2017 at 11:53:13AM -0700, Luis R. Rodriguez wrote: > Now that all filesystems which used to rely on kthread > freezing have been converted to filesystem freeze/thawing > we can remove the kernel kthread freezer. Really? There's no other subsystem that relies on kernel thread and

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 3 Oct 2017, Pavel Machek wrote: > > Again, I agree that the (rare) kthreads that are actually "creating" new > > I/O have to be somehow frozen and require special care. > > Agreed. Was any effort made to identify those special kernel threads? I don't think there is any other way than

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 3 Oct 2017, Pavel Machek wrote: > > Again, I agree that the (rare) kthreads that are actually "creating" new > > I/O have to be somehow frozen and require special care. > > Agreed. Was any effort made to identify those special kernel threads? I don't think there is any other way than

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue 2017-10-03 22:38:33, Jiri Kosina wrote: > On Tue, 3 Oct 2017, Pavel Machek wrote: > > > > This point I don't understand. What exactly do you mean? > > > > Hibernation: > > > > We freeze, do system snapshot, unfreeze, and write image to > > disk. > > Where/why do you unfreeze between

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue 2017-10-03 22:38:33, Jiri Kosina wrote: > On Tue, 3 Oct 2017, Pavel Machek wrote: > > > > This point I don't understand. What exactly do you mean? > > > > Hibernation: > > > > We freeze, do system snapshot, unfreeze, and write image to > > disk. > > Where/why do you unfreeze between

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 3 Oct 2017, Jiri Kosina wrote: > > What about the many drivers outside filesystems that use the > > set_freezable() / try_to_freeze() / wait_event_freezable() API? > > Many/most of them are just completely bogus and pointless. More specifically -- they don't really care at all whether

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 3 Oct 2017, Jiri Kosina wrote: > > What about the many drivers outside filesystems that use the > > set_freezable() / try_to_freeze() / wait_event_freezable() API? > > Many/most of them are just completely bogus and pointless. More specifically -- they don't really care at all whether

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, Oct 03, 2017 at 10:12:04PM +0200, Pavel Machek wrote: > On Tue 2017-10-03 11:53:13, Luis R. Rodriguez wrote: > > Now that all filesystems which used to rely on kthread > > freezing have been converted to filesystem freeze/thawing > > we can remove the kernel kthread freezer. > > Are you

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, Oct 03, 2017 at 10:12:04PM +0200, Pavel Machek wrote: > On Tue 2017-10-03 11:53:13, Luis R. Rodriguez wrote: > > Now that all filesystems which used to rely on kthread > > freezing have been converted to filesystem freeze/thawing > > we can remove the kernel kthread freezer. > > Are you

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, Oct 3, 2017 at 10:38 PM, Jiri Kosina wrote: > On Tue, 3 Oct 2017, Pavel Machek wrote: > >> > This point I don't understand. What exactly do you mean? >> >> Hibernation: >> >> We freeze, do system snapshot, unfreeze, and write image to >> disk. > > Where/why do you

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, Oct 3, 2017 at 10:38 PM, Jiri Kosina wrote: > On Tue, 3 Oct 2017, Pavel Machek wrote: > >> > This point I don't understand. What exactly do you mean? >> >> Hibernation: >> >> We freeze, do system snapshot, unfreeze, and write image to >> disk. > > Where/why do you unfreeze between

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 3 Oct 2017, Pavel Machek wrote: > > This point I don't understand. What exactly do you mean? > > Hibernation: > > We freeze, do system snapshot, unfreeze, and write image to > disk. Where/why do you unfreeze between creating the snapshot and writing it out? Again, I agree that the

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 3 Oct 2017, Pavel Machek wrote: > > This point I don't understand. What exactly do you mean? > > Hibernation: > > We freeze, do system snapshot, unfreeze, and write image to > disk. Where/why do you unfreeze between creating the snapshot and writing it out? Again, I agree that the

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, Oct 03, 2017 at 08:21:42PM +, Bart Van Assche wrote: > On Tue, 2017-10-03 at 22:17 +0200, Jiri Kosina wrote: > > On Tue, 3 Oct 2017, Bart Van Assche wrote: > > > What about the many drivers outside filesystems that use the > > > set_freezable() / try_to_freeze() /

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, Oct 03, 2017 at 08:21:42PM +, Bart Van Assche wrote: > On Tue, 2017-10-03 at 22:17 +0200, Jiri Kosina wrote: > > On Tue, 3 Oct 2017, Bart Van Assche wrote: > > > What about the many drivers outside filesystems that use the > > > set_freezable() / try_to_freeze() /

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 3 Oct 2017, Bart Van Assche wrote: > If just a single driver would use that API to prevent that I/O occurs while > processes are frozen then this patch will break that driver. I would like to > know your opinion about the following patch in particular: "[PATCH v4 1/7] md: > Make md resync

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 3 Oct 2017, Bart Van Assche wrote: > If just a single driver would use that API to prevent that I/O occurs while > processes are frozen then this patch will break that driver. I would like to > know your opinion about the following patch in particular: "[PATCH v4 1/7] md: > Make md resync

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 2017-10-03 at 22:17 +0200, Jiri Kosina wrote: > On Tue, 3 Oct 2017, Bart Van Assche wrote: > > What about the many drivers outside filesystems that use the > > set_freezable() / try_to_freeze() / wait_event_freezable() API? > > Many/most of them are just completely bogus and pointless.

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 2017-10-03 at 22:17 +0200, Jiri Kosina wrote: > On Tue, 3 Oct 2017, Bart Van Assche wrote: > > What about the many drivers outside filesystems that use the > > set_freezable() / try_to_freeze() / wait_event_freezable() API? > > Many/most of them are just completely bogus and pointless.

Re: [RFC 5/5] pm: remove kernel thread freezing

Hi! > > Can memory management doing background writes be a problem? > > This point I don't understand. What exactly do you mean? Hibernation: We freeze, do system snapshot, unfreeze, and write image to disk. Memory management wakes up (this used to be called bdflush), decides its time to write

Re: [RFC 5/5] pm: remove kernel thread freezing

Hi! > > Can memory management doing background writes be a problem? > > This point I don't understand. What exactly do you mean? Hibernation: We freeze, do system snapshot, unfreeze, and write image to disk. Memory management wakes up (this used to be called bdflush), decides its time to write

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 3 Oct 2017, Bart Van Assche wrote: > What about the many drivers outside filesystems that use the > set_freezable() / try_to_freeze() / wait_event_freezable() API? Many/most of them are just completely bogus and pointless. I've killed a lot of those in the past, but the copy/paste

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 3 Oct 2017, Bart Van Assche wrote: > What about the many drivers outside filesystems that use the > set_freezable() / try_to_freeze() / wait_event_freezable() API? Many/most of them are just completely bogus and pointless. I've killed a lot of those in the past, but the copy/paste

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 3 Oct 2017, Pavel Machek wrote: > Can knfsd be a problem? It'd actually be useful to walk through all the 'try_to_freeze()' instances in kthreads, and analyze those. I've started this effort, and as a result I removed most of them; but there are still quite a few remaining. And knfsd

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 3 Oct 2017, Pavel Machek wrote: > Can knfsd be a problem? It'd actually be useful to walk through all the 'try_to_freeze()' instances in kthreads, and analyze those. I've started this effort, and as a result I removed most of them; but there are still quite a few remaining. And knfsd

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 2017-10-03 at 11:53 -0700, Luis R. Rodriguez wrote: > Now that all filesystems which used to rely on kthread > freezing have been converted to filesystem freeze/thawing > we can remove the kernel kthread freezer. Many subsystems use system_freezable_wq and/or

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue, 2017-10-03 at 11:53 -0700, Luis R. Rodriguez wrote: > Now that all filesystems which used to rely on kthread > freezing have been converted to filesystem freeze/thawing > we can remove the kernel kthread freezer. Many subsystems use system_freezable_wq and/or

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue 2017-10-03 11:53:13, Luis R. Rodriguez wrote: > Now that all filesystems which used to rely on kthread > freezing have been converted to filesystem freeze/thawing > we can remove the kernel kthread freezer. Are you surely-sure? You mentioned other in kernel sources of writes; what about

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tue 2017-10-03 11:53:13, Luis R. Rodriguez wrote: > Now that all filesystems which used to rely on kthread > freezing have been converted to filesystem freeze/thawing > we can remove the kernel kthread freezer. Are you surely-sure? You mentioned other in kernel sources of writes; what about

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tuesday, October 3, 2017 8:53:13 PM CEST Luis R. Rodriguez wrote: > Now that all filesystems which used to rely on kthread > freezing have been converted to filesystem freeze/thawing > we can remove the kernel kthread freezer. > > Signed-off-by: Luis R. Rodriguez I like

Re: [RFC 5/5] pm: remove kernel thread freezing

On Tuesday, October 3, 2017 8:53:13 PM CEST Luis R. Rodriguez wrote: > Now that all filesystems which used to rely on kthread > freezing have been converted to filesystem freeze/thawing > we can remove the kernel kthread freezer. > > Signed-off-by: Luis R. Rodriguez I like this one. :-)

[RFC 5/5] pm: remove kernel thread freezing

Now that all filesystems which used to rely on kthread freezing have been converted to filesystem freeze/thawing we can remove the kernel kthread freezer. Signed-off-by: Luis R. Rodriguez --- Documentation/power/freezing-of-tasks.txt | 9 -- drivers/xen/manage.c

[RFC 5/5] pm: remove kernel thread freezing

Now that all filesystems which used to rely on kthread freezing have been converted to filesystem freeze/thawing we can remove the kernel kthread freezer. Signed-off-by: Luis R. Rodriguez --- Documentation/power/freezing-of-tasks.txt | 9 -- drivers/xen/manage.c | 6