Re: [RFC PATCH 3/3] mm: support free hugepage pre zero out
> > Free page reporting in virtio-balloon doesn't give you any guarantees
> > regarding zeroing of pages. Take a look at the QEMU implementation -
> > e.g., with vfio all reports are simply ignored.
> >
> > Also, I am not sure if mangling such details ("zeroing of pages") into
> > the page reporting infrastructure is a good idea.
> >
>
> Oh, now I get what you are doing here, you rely on zero_free_pages of
> your other patch series and are not relying on virtio-balloon free page
> reporting to do the zeroing.
>
> You really should have mentioned that this patch series relies on the
> other one and in which way.
I am sorry for that. After I sent out the patch, I realized I should
mention that, so I sent out an updated version which added the
information you mentioned :)
Thanks !
Liang
Re: [RFC PATCH 3/3] mm: support free hugepage pre zero out
On 22.12.20 09:31, David Hildenbrand wrote:
> On 22.12.20 08:49, Liang Li wrote:
>> This patch add support of pre zero out free hugepage, we can use
>> this feature to speed up page population and page fault handing.
>>
>> Cc: Alexander Duyck
>> Cc: Mel Gorman
>> Cc: Andrea Arcangeli
>> Cc: Dan Williams
>> Cc: Dave Hansen
>> Cc: David Hildenbrand
>> Cc: Michal Hocko
>> Cc: Andrew Morton
>> Cc: Alex Williamson
>> Cc: Michael S. Tsirkin
>> Cc: Jason Wang
>> Cc: Mike Kravetz
>> Cc: Liang Li
>> Signed-off-by: Liang Li
>> ---
>> mm/page_prezero.c | 17 +
>> 1 file changed, 17 insertions(+)
>>
>> diff --git a/mm/page_prezero.c b/mm/page_prezero.c
>> index c8ce720bfc54..dff4e0adf402 100644
>> --- a/mm/page_prezero.c
>> +++ b/mm/page_prezero.c
>> @@ -26,6 +26,7 @@ static unsigned long delay_millisecs = 1000;
>> static unsigned long zeropage_enable __read_mostly;
>> static DEFINE_MUTEX(kzeropaged_mutex);
>> static struct page_reporting_dev_info zero_page_dev_info;
>> +static struct page_reporting_dev_info zero_hugepage_dev_info;
>>
>> inline void clear_zero_page_flag(struct page *page, int order)
>> {
>> @@ -69,9 +70,17 @@ static int start_kzeropaged(void)
>> zero_page_dev_info.delay_jiffies =
>> msecs_to_jiffies(delay_millisecs);
>>
>> err = page_reporting_register(_page_dev_info);
>> +
>> +zero_hugepage_dev_info.report = zero_free_pages;
>> +zero_hugepage_dev_info.mini_order = mini_page_order;
>> +zero_hugepage_dev_info.batch_size = batch_size;
>> +zero_hugepage_dev_info.delay_jiffies =
>> msecs_to_jiffies(delay_millisecs);
>> +
>> +err |= hugepage_reporting_register(_hugepage_dev_info);
>> pr_info("Zero page enabled\n");
>> } else {
>> page_reporting_unregister(_page_dev_info);
>> +hugepage_reporting_unregister(_hugepage_dev_info);
>> pr_info("Zero page disabled\n");
>> }
>>
>> @@ -90,7 +99,15 @@ static int restart_kzeropaged(void)
>> zero_page_dev_info.batch_size = batch_size;
>> zero_page_dev_info.delay_jiffies =
>> msecs_to_jiffies(delay_millisecs);
>>
>> +hugepage_reporting_unregister(_hugepage_dev_info);
>> +
>> +zero_hugepage_dev_info.report = zero_free_pages;
>> +zero_hugepage_dev_info.mini_order = mini_page_order;
>> +zero_hugepage_dev_info.batch_size = batch_size;
>> +zero_hugepage_dev_info.delay_jiffies =
>> msecs_to_jiffies(delay_millisecs);
>> +
>> err = page_reporting_register(_page_dev_info);
>> +err |= hugepage_reporting_register(_hugepage_dev_info);
>> pr_info("Zero page enabled\n");
>> }
>>
>>
>
> Free page reporting in virtio-balloon doesn't give you any guarantees
> regarding zeroing of pages. Take a look at the QEMU implementation -
> e.g., with vfio all reports are simply ignored.
>
> Also, I am not sure if mangling such details ("zeroing of pages") into
> the page reporting infrastructure is a good idea.
>
Oh, now I get what you are doing here, you rely on zero_free_pages of
your other patch series and are not relying on virtio-balloon free page
reporting to do the zeroing.
You really should have mentioned that this patch series relies on the
other one and in which way.
--
Thanks,
David / dhildenb
Re: [RFC PATCH 3/3] mm: support free hugepage pre zero out
On 22.12.20 08:49, Liang Li wrote:
> This patch add support of pre zero out free hugepage, we can use
> this feature to speed up page population and page fault handing.
>
> Cc: Alexander Duyck
> Cc: Mel Gorman
> Cc: Andrea Arcangeli
> Cc: Dan Williams
> Cc: Dave Hansen
> Cc: David Hildenbrand
> Cc: Michal Hocko
> Cc: Andrew Morton
> Cc: Alex Williamson
> Cc: Michael S. Tsirkin
> Cc: Jason Wang
> Cc: Mike Kravetz
> Cc: Liang Li
> Signed-off-by: Liang Li
> ---
> mm/page_prezero.c | 17 +
> 1 file changed, 17 insertions(+)
>
> diff --git a/mm/page_prezero.c b/mm/page_prezero.c
> index c8ce720bfc54..dff4e0adf402 100644
> --- a/mm/page_prezero.c
> +++ b/mm/page_prezero.c
> @@ -26,6 +26,7 @@ static unsigned long delay_millisecs = 1000;
> static unsigned long zeropage_enable __read_mostly;
> static DEFINE_MUTEX(kzeropaged_mutex);
> static struct page_reporting_dev_info zero_page_dev_info;
> +static struct page_reporting_dev_info zero_hugepage_dev_info;
>
> inline void clear_zero_page_flag(struct page *page, int order)
> {
> @@ -69,9 +70,17 @@ static int start_kzeropaged(void)
> zero_page_dev_info.delay_jiffies =
> msecs_to_jiffies(delay_millisecs);
>
> err = page_reporting_register(_page_dev_info);
> +
> + zero_hugepage_dev_info.report = zero_free_pages;
> + zero_hugepage_dev_info.mini_order = mini_page_order;
> + zero_hugepage_dev_info.batch_size = batch_size;
> + zero_hugepage_dev_info.delay_jiffies =
> msecs_to_jiffies(delay_millisecs);
> +
> + err |= hugepage_reporting_register(_hugepage_dev_info);
> pr_info("Zero page enabled\n");
> } else {
> page_reporting_unregister(_page_dev_info);
> + hugepage_reporting_unregister(_hugepage_dev_info);
> pr_info("Zero page disabled\n");
> }
>
> @@ -90,7 +99,15 @@ static int restart_kzeropaged(void)
> zero_page_dev_info.batch_size = batch_size;
> zero_page_dev_info.delay_jiffies =
> msecs_to_jiffies(delay_millisecs);
>
> + hugepage_reporting_unregister(_hugepage_dev_info);
> +
> + zero_hugepage_dev_info.report = zero_free_pages;
> + zero_hugepage_dev_info.mini_order = mini_page_order;
> + zero_hugepage_dev_info.batch_size = batch_size;
> + zero_hugepage_dev_info.delay_jiffies =
> msecs_to_jiffies(delay_millisecs);
> +
> err = page_reporting_register(_page_dev_info);
> + err |= hugepage_reporting_register(_hugepage_dev_info);
> pr_info("Zero page enabled\n");
> }
>
>
Free page reporting in virtio-balloon doesn't give you any guarantees
regarding zeroing of pages. Take a look at the QEMU implementation -
e.g., with vfio all reports are simply ignored.
Also, I am not sure if mangling such details ("zeroing of pages") into
the page reporting infrastructure is a good idea.
--
Thanks,
David / dhildenb
[RFC PATCH 3/3] mm: support free hugepage pre zero out
This patch add support of pre zero out free hugepage, we can use
this feature to speed up page population and page fault handing.
Cc: Alexander Duyck
Cc: Mel Gorman
Cc: Andrea Arcangeli
Cc: Dan Williams
Cc: Dave Hansen
Cc: David Hildenbrand
Cc: Michal Hocko
Cc: Andrew Morton
Cc: Alex Williamson
Cc: Michael S. Tsirkin
Cc: Jason Wang
Cc: Mike Kravetz
Cc: Liang Li
Signed-off-by: Liang Li
---
mm/page_prezero.c | 17 +
1 file changed, 17 insertions(+)
diff --git a/mm/page_prezero.c b/mm/page_prezero.c
index c8ce720bfc54..dff4e0adf402 100644
--- a/mm/page_prezero.c
+++ b/mm/page_prezero.c
@@ -26,6 +26,7 @@ static unsigned long delay_millisecs = 1000;
static unsigned long zeropage_enable __read_mostly;
static DEFINE_MUTEX(kzeropaged_mutex);
static struct page_reporting_dev_info zero_page_dev_info;
+static struct page_reporting_dev_info zero_hugepage_dev_info;
inline void clear_zero_page_flag(struct page *page, int order)
{
@@ -69,9 +70,17 @@ static int start_kzeropaged(void)
zero_page_dev_info.delay_jiffies =
msecs_to_jiffies(delay_millisecs);
err = page_reporting_register(_page_dev_info);
+
+ zero_hugepage_dev_info.report = zero_free_pages;
+ zero_hugepage_dev_info.mini_order = mini_page_order;
+ zero_hugepage_dev_info.batch_size = batch_size;
+ zero_hugepage_dev_info.delay_jiffies =
msecs_to_jiffies(delay_millisecs);
+
+ err |= hugepage_reporting_register(_hugepage_dev_info);
pr_info("Zero page enabled\n");
} else {
page_reporting_unregister(_page_dev_info);
+ hugepage_reporting_unregister(_hugepage_dev_info);
pr_info("Zero page disabled\n");
}
@@ -90,7 +99,15 @@ static int restart_kzeropaged(void)
zero_page_dev_info.batch_size = batch_size;
zero_page_dev_info.delay_jiffies =
msecs_to_jiffies(delay_millisecs);
+ hugepage_reporting_unregister(_hugepage_dev_info);
+
+ zero_hugepage_dev_info.report = zero_free_pages;
+ zero_hugepage_dev_info.mini_order = mini_page_order;
+ zero_hugepage_dev_info.batch_size = batch_size;
+ zero_hugepage_dev_info.delay_jiffies =
msecs_to_jiffies(delay_millisecs);
+
err = page_reporting_register(_page_dev_info);
+ err |= hugepage_reporting_register(_hugepage_dev_info);
pr_info("Zero page enabled\n");
}
--
2.18.2
