| Message ID | 87twmki2ew.fsf@vitty.brq.redhat.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Mon, Jan 11, 2016 at 04:03:35PM +0100, Vitaly Kuznetsov wrote: > Daniel Kiper <daniel.kiper@oracle.com> writes: > > [skip] > > >> > > And we want to have it working out of the box. > >> > > So, I think that we should find proper solution. I suppose that we can schedule > >> > > a task here which auto online attached blocks. Hmmm... Not nice but should work. > >> > > Or maybe you have better idea how to fix this issue. > >> > > >> > I'd like to avoid additional delays and memory allocations between > >> > adding new memory and onlining it (and this is the main purpose of the > >> > patch). Maybe we can have a tristate online parameter ('online_now', > >> > 'online_delay', 'keep_offlined') and handle it > >> > accordingly. Alternatively I can suggest we have the onlining in Xen > >> > balloon driver code, memhp_auto_online is exported so we can call > >> > online_pages() after we release the ballon_mutex. > >> > >> This is not nice too. I prefer the same code path for every case. > >> Give me some time. I will think how to solve that issue. > > > > It looks that we can safely call mutex_unlock() just before add_memory_resource() > > call and retake lock immediately after add_memory_resource(). add_memory_resource() > > itself does not play with balloon stuff and even if online_pages() does then it > > take balloon_mutex in right place. Additionally, only one balloon task can run, > > so, I think that we are on safe side. Am I right? > > I think you are as balloon_mutex is internal to xen driver and there is > only one balloon_process() running at the time. I just smoke-tested the > following: > > commit 0fce4746a0090d533e9302cc42b3d3c0645d756d > Author: Vitaly Kuznetsov <vkuznets@redhat.com> > Date: Mon Jan 11 14:22:11 2016 +0100 > > xen_balloon: make hotplug auto online work > > Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> > > diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c > index 890c3b5..08bbf35 100644 > --- a/drivers/xen/balloon.c > +++ b/drivers/xen/balloon.c > @@ -338,7 +338,10 @@ static enum bp_state reserve_additional_memory(void) > } > #endif > > - rc = add_memory_resource(nid, resource, false); > + mutex_unlock(&balloon_mutex); > + rc = add_memory_resource(nid, resource, memhp_auto_online); > + mutex_lock(&balloon_mutex); > + > if (rc) { > pr_warn("Cannot add additional memory (%i)\n", rc); > goto err; > @@ -565,8 +568,10 @@ static void balloon_process(struct work_struct *work) > if (credit > 0) { > if (balloon_is_inflated()) > state = increase_reservation(credit); > - else > + else { > + printk("balloon_process: adding memory (credit: %ld)!\n", credit); > state = reserve_additional_memory(); > + } > } > > if (credit < 0) > > And it seems to work (unrelated rant: 'xl mem-set' after 'xl max-mem' Great! Thanks! Let's go further. Please add bool online argument to reserve_additional_memory() and then call add_memory_resource() with it. Then call reserve_additional_memory() with memhp_auto_online from balloon_process() and with false from add_ballooned_pages(). Voila! Please do not forget to add comment for mutex_unlock() and mutex_lock() around add_memory_resource() (why it is needed and why it works correctly). > doesn't work with "libxl: error: libxl.c:4809:libxl_set_memory_target: > memory_dynamic_max must be less than or equal to memory_static_max". At Ignore that. It must be fixed and it is on my TODO list. However, I am busy with more important stuff right now. Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Jan 11, 2016 at 05:22:58PM +0100, Daniel Kiper wrote: > On Mon, Jan 11, 2016 at 04:03:35PM +0100, Vitaly Kuznetsov wrote: > > Daniel Kiper <daniel.kiper@oracle.com> writes: > > > > [skip] > > > > >> > > And we want to have it working out of the box. > > >> > > So, I think that we should find proper solution. I suppose that we can schedule > > >> > > a task here which auto online attached blocks. Hmmm... Not nice but should work. > > >> > > Or maybe you have better idea how to fix this issue. > > >> > > > >> > I'd like to avoid additional delays and memory allocations between > > >> > adding new memory and onlining it (and this is the main purpose of the > > >> > patch). Maybe we can have a tristate online parameter ('online_now', > > >> > 'online_delay', 'keep_offlined') and handle it > > >> > accordingly. Alternatively I can suggest we have the onlining in Xen > > >> > balloon driver code, memhp_auto_online is exported so we can call > > >> > online_pages() after we release the ballon_mutex. > > >> > > >> This is not nice too. I prefer the same code path for every case. > > >> Give me some time. I will think how to solve that issue. > > > > > > It looks that we can safely call mutex_unlock() just before add_memory_resource() > > > call and retake lock immediately after add_memory_resource(). add_memory_resource() > > > itself does not play with balloon stuff and even if online_pages() does then it > > > take balloon_mutex in right place. Additionally, only one balloon task can run, > > > so, I think that we are on safe side. Am I right? > > > > I think you are as balloon_mutex is internal to xen driver and there is > > only one balloon_process() running at the time. I just smoke-tested the > > following: > > > > commit 0fce4746a0090d533e9302cc42b3d3c0645d756d > > Author: Vitaly Kuznetsov <vkuznets@redhat.com> > > Date: Mon Jan 11 14:22:11 2016 +0100 > > > > xen_balloon: make hotplug auto online work > > > > Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> > > > > diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c > > index 890c3b5..08bbf35 100644 > > --- a/drivers/xen/balloon.c > > +++ b/drivers/xen/balloon.c > > @@ -338,7 +338,10 @@ static enum bp_state reserve_additional_memory(void) > > } > > #endif > > > > - rc = add_memory_resource(nid, resource, false); > > + mutex_unlock(&balloon_mutex); > > + rc = add_memory_resource(nid, resource, memhp_auto_online); > > + mutex_lock(&balloon_mutex); > > + > > if (rc) { > > pr_warn("Cannot add additional memory (%i)\n", rc); > > goto err; > > @@ -565,8 +568,10 @@ static void balloon_process(struct work_struct *work) > > if (credit > 0) { > > if (balloon_is_inflated()) > > state = increase_reservation(credit); > > - else > > + else { > > + printk("balloon_process: adding memory (credit: %ld)!\n", credit); > > state = reserve_additional_memory(); > > + } > > } > > > > if (credit < 0) > > > > And it seems to work (unrelated rant: 'xl mem-set' after 'xl max-mem' > > Great! Thanks! > > Let's go further. Please add bool online argument to reserve_additional_memory() and > then call add_memory_resource() with it. Then call reserve_additional_memory() with > memhp_auto_online from balloon_process() and with false from add_ballooned_pages(). Voila! > > Please do not forget to add comment for mutex_unlock() and mutex_lock() > around add_memory_resource() (why it is needed and why it works correctly). I forgot about one thing. Please update help for XEN_BALLOON_MEMORY_HOTPLUG config option accordingly. Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 890c3b5..08bbf35 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -338,7 +338,10 @@ static enum bp_state reserve_additional_memory(void) } #endif - rc = add_memory_resource(nid, resource, false); + mutex_unlock(&balloon_mutex); + rc = add_memory_resource(nid, resource, memhp_auto_online); + mutex_lock(&balloon_mutex); + if (rc) { pr_warn("Cannot add additional memory (%i)\n", rc); goto err; @@ -565,8 +568,10 @@ static void balloon_process(struct work_struct *work) if (credit > 0) { if (balloon_is_inflated()) state = increase_reservation(credit); - else + else { + printk("balloon_process: adding memory (credit: %ld)!\n", credit); state = reserve_additional_memory(); + } } if (credit < 0)