* [Qemu-devel] [PATCH 0/2] migration/postcopy: simplify postcopy_chunk_hostpages_pass
@ 2019-08-06 0:46 Wei Yang
2019-08-06 0:46 ` [Qemu-devel] [PATCH 1/2] migration/postcopy: simplify calculation of run_start and fixup_start_addr Wei Yang
` (2 more replies)
0 siblings, 3 replies; 7+ messages in thread
From: Wei Yang @ 2019-08-06 0:46 UTC (permalink / raw)
To: qemu-devel; +Cc: Wei Yang, dgilbert, quintela
When looking into function postcopy_chunk_hostpages_pass(), we could use
alignment calculation to simplify it.
Wei Yang (2):
migration/postcopy: simplify calculation of run_start and
fixup_start_addr
migration/postcopy: use QEMU_IS_ALIGNED to replace host_offset
migration/ram.c | 37 +++++++------------------------------
1 file changed, 7 insertions(+), 30 deletions(-)
--
2.17.1
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Qemu-devel] [PATCH 1/2] migration/postcopy: simplify calculation of run_start and fixup_start_addr
2019-08-06 0:46 [Qemu-devel] [PATCH 0/2] migration/postcopy: simplify postcopy_chunk_hostpages_pass Wei Yang
@ 2019-08-06 0:46 ` Wei Yang
2019-08-06 14:51 ` Dr. David Alan Gilbert
2019-08-06 0:46 ` [Qemu-devel] [PATCH 2/2] migration/postcopy: use QEMU_IS_ALIGNED to replace host_offset Wei Yang
2019-08-07 18:43 ` [Qemu-devel] [PATCH 0/2] migration/postcopy: simplify postcopy_chunk_hostpages_pass Dr. David Alan Gilbert
2 siblings, 1 reply; 7+ messages in thread
From: Wei Yang @ 2019-08-06 0:46 UTC (permalink / raw)
To: qemu-devel; +Cc: Wei Yang, dgilbert, quintela
The purpose of the calculation is to find a HostPage which is partially
dirty.
* fixup_start_addr points to the start of the HostPage to discard
* run_start points to the next HostPage to check
While in the middle stage, there would two cases for run_start:
* aligned with HostPage means this is not partially dirty
* not aligned means this is partially dirty
When it is aligned, no work and calculation is necessary. run_start
already points to the start of next HostPage and is ready to continue.
When it is not aligned, the calculation could be simplified with:
* fixup_start_addr = QEMU_ALIGN_DOWN(run_start, host_ratio)
* run_start = QEMU_ALIGN_UP(run_start, host_ratio)
By doing so, run_start always points to the next HostPage to check.
fixup_start_addr always points to the HostPage to discard.
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
---
migration/ram.c | 34 +++++++---------------------------
1 file changed, 7 insertions(+), 27 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index c9585487ac..d86661a015 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2956,7 +2956,6 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
}
while (run_start < pages) {
- unsigned long fixup_start_addr;
unsigned long host_offset;
/*
@@ -2964,45 +2963,26 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
* page, then we need to fixup this host page.
*/
host_offset = run_start % host_ratio;
- if (host_offset) {
- fixup_start_addr = run_start - host_offset;
- /*
- * This host page has gone, the next loop iteration starts
- * from after the fixup
- */
- run_start = fixup_start_addr + host_ratio;
- } else {
+ if (!host_offset) {
/* Find the end of this run */
- unsigned long run_end;
if (unsent_pass) {
- run_end = find_next_bit(unsentmap, pages, run_start + 1);
+ run_start = find_next_bit(unsentmap, pages, run_start + 1);
} else {
- run_end = find_next_zero_bit(bitmap, pages, run_start + 1);
+ run_start = find_next_zero_bit(bitmap, pages, run_start + 1);
}
/*
* If the end isn't at the start of a host page, then the
* run doesn't finish at the end of a host page
* and we need to discard.
*/
- host_offset = run_end % host_ratio;
- if (host_offset) {
- fixup_start_addr = run_end - host_offset;
- /*
- * This host page has gone, the next loop iteration starts
- * from after the fixup
- */
- run_start = fixup_start_addr + host_ratio;
- } else {
- /*
- * No discards on this iteration, next loop starts from
- * next sent/dirty page
- */
- run_start = run_end + 1;
- }
+ host_offset = run_start % host_ratio;
}
if (host_offset) {
unsigned long page;
+ unsigned long fixup_start_addr = QEMU_ALIGN_DOWN(run_start,
+ host_ratio);
+ run_start = QEMU_ALIGN_UP(run_start, host_ratio);
/* Tell the destination to discard this page */
if (unsent_pass || !test_bit(fixup_start_addr, unsentmap)) {
--
2.17.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [Qemu-devel] [PATCH 2/2] migration/postcopy: use QEMU_IS_ALIGNED to replace host_offset
2019-08-06 0:46 [Qemu-devel] [PATCH 0/2] migration/postcopy: simplify postcopy_chunk_hostpages_pass Wei Yang
2019-08-06 0:46 ` [Qemu-devel] [PATCH 1/2] migration/postcopy: simplify calculation of run_start and fixup_start_addr Wei Yang
@ 2019-08-06 0:46 ` Wei Yang
2019-08-06 15:47 ` Dr. David Alan Gilbert
2019-08-07 18:43 ` [Qemu-devel] [PATCH 0/2] migration/postcopy: simplify postcopy_chunk_hostpages_pass Dr. David Alan Gilbert
2 siblings, 1 reply; 7+ messages in thread
From: Wei Yang @ 2019-08-06 0:46 UTC (permalink / raw)
To: qemu-devel; +Cc: Wei Yang, dgilbert, quintela
Use QEMU_IS_ALIGNED for the check, it would be more consistent with
other align calculations.
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
---
migration/ram.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index d86661a015..dfbf71c580 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2956,14 +2956,12 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
}
while (run_start < pages) {
- unsigned long host_offset;
/*
* If the start of this run of pages is in the middle of a host
* page, then we need to fixup this host page.
*/
- host_offset = run_start % host_ratio;
- if (!host_offset) {
+ if (QEMU_IS_ALIGNED(run_start, host_ratio)) {
/* Find the end of this run */
if (unsent_pass) {
run_start = find_next_bit(unsentmap, pages, run_start + 1);
@@ -2975,10 +2973,9 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
* run doesn't finish at the end of a host page
* and we need to discard.
*/
- host_offset = run_start % host_ratio;
}
- if (host_offset) {
+ if (!QEMU_IS_ALIGNED(run_start, host_ratio)) {
unsigned long page;
unsigned long fixup_start_addr = QEMU_ALIGN_DOWN(run_start,
host_ratio);
--
2.17.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [Qemu-devel] [PATCH 1/2] migration/postcopy: simplify calculation of run_start and fixup_start_addr
2019-08-06 0:46 ` [Qemu-devel] [PATCH 1/2] migration/postcopy: simplify calculation of run_start and fixup_start_addr Wei Yang
@ 2019-08-06 14:51 ` Dr. David Alan Gilbert
2019-08-07 0:14 ` Wei Yang
0 siblings, 1 reply; 7+ messages in thread
From: Dr. David Alan Gilbert @ 2019-08-06 14:51 UTC (permalink / raw)
To: Wei Yang; +Cc: qemu-devel, quintela
* Wei Yang (richardw.yang@linux.intel.com) wrote:
> The purpose of the calculation is to find a HostPage which is partially
> dirty.
>
> * fixup_start_addr points to the start of the HostPage to discard
> * run_start points to the next HostPage to check
>
> While in the middle stage, there would two cases for run_start:
>
> * aligned with HostPage means this is not partially dirty
> * not aligned means this is partially dirty
>
> When it is aligned, no work and calculation is necessary. run_start
> already points to the start of next HostPage and is ready to continue.
>
> When it is not aligned, the calculation could be simplified with:
>
> * fixup_start_addr = QEMU_ALIGN_DOWN(run_start, host_ratio)
> * run_start = QEMU_ALIGN_UP(run_start, host_ratio)
>
> By doing so, run_start always points to the next HostPage to check.
> fixup_start_addr always points to the HostPage to discard.
>
> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Yes that's a lot shorter; note it doess it on top of your cleanup
from a couple of weeks back.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
> migration/ram.c | 34 +++++++---------------------------
> 1 file changed, 7 insertions(+), 27 deletions(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index c9585487ac..d86661a015 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -2956,7 +2956,6 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
> }
>
> while (run_start < pages) {
> - unsigned long fixup_start_addr;
> unsigned long host_offset;
>
> /*
> @@ -2964,45 +2963,26 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
> * page, then we need to fixup this host page.
> */
> host_offset = run_start % host_ratio;
> - if (host_offset) {
> - fixup_start_addr = run_start - host_offset;
> - /*
> - * This host page has gone, the next loop iteration starts
> - * from after the fixup
> - */
> - run_start = fixup_start_addr + host_ratio;
> - } else {
> + if (!host_offset) {
> /* Find the end of this run */
> - unsigned long run_end;
> if (unsent_pass) {
> - run_end = find_next_bit(unsentmap, pages, run_start + 1);
> + run_start = find_next_bit(unsentmap, pages, run_start + 1);
> } else {
> - run_end = find_next_zero_bit(bitmap, pages, run_start + 1);
> + run_start = find_next_zero_bit(bitmap, pages, run_start + 1);
> }
> /*
> * If the end isn't at the start of a host page, then the
> * run doesn't finish at the end of a host page
> * and we need to discard.
> */
> - host_offset = run_end % host_ratio;
> - if (host_offset) {
> - fixup_start_addr = run_end - host_offset;
> - /*
> - * This host page has gone, the next loop iteration starts
> - * from after the fixup
> - */
> - run_start = fixup_start_addr + host_ratio;
> - } else {
> - /*
> - * No discards on this iteration, next loop starts from
> - * next sent/dirty page
> - */
> - run_start = run_end + 1;
> - }
> + host_offset = run_start % host_ratio;
> }
>
> if (host_offset) {
> unsigned long page;
> + unsigned long fixup_start_addr = QEMU_ALIGN_DOWN(run_start,
> + host_ratio);
> + run_start = QEMU_ALIGN_UP(run_start, host_ratio);
>
> /* Tell the destination to discard this page */
> if (unsent_pass || !test_bit(fixup_start_addr, unsentmap)) {
> --
> 2.17.1
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Qemu-devel] [PATCH 2/2] migration/postcopy: use QEMU_IS_ALIGNED to replace host_offset
2019-08-06 0:46 ` [Qemu-devel] [PATCH 2/2] migration/postcopy: use QEMU_IS_ALIGNED to replace host_offset Wei Yang
@ 2019-08-06 15:47 ` Dr. David Alan Gilbert
0 siblings, 0 replies; 7+ messages in thread
From: Dr. David Alan Gilbert @ 2019-08-06 15:47 UTC (permalink / raw)
To: Wei Yang; +Cc: qemu-devel, quintela
* Wei Yang (richardw.yang@linux.intel.com) wrote:
> Use QEMU_IS_ALIGNED for the check, it would be more consistent with
> other align calculations.
>
> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
> migration/ram.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index d86661a015..dfbf71c580 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -2956,14 +2956,12 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
> }
>
> while (run_start < pages) {
> - unsigned long host_offset;
>
> /*
> * If the start of this run of pages is in the middle of a host
> * page, then we need to fixup this host page.
> */
> - host_offset = run_start % host_ratio;
> - if (!host_offset) {
> + if (QEMU_IS_ALIGNED(run_start, host_ratio)) {
> /* Find the end of this run */
> if (unsent_pass) {
> run_start = find_next_bit(unsentmap, pages, run_start + 1);
> @@ -2975,10 +2973,9 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
> * run doesn't finish at the end of a host page
> * and we need to discard.
> */
> - host_offset = run_start % host_ratio;
> }
>
> - if (host_offset) {
> + if (!QEMU_IS_ALIGNED(run_start, host_ratio)) {
> unsigned long page;
> unsigned long fixup_start_addr = QEMU_ALIGN_DOWN(run_start,
> host_ratio);
> --
> 2.17.1
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Qemu-devel] [PATCH 1/2] migration/postcopy: simplify calculation of run_start and fixup_start_addr
2019-08-06 14:51 ` Dr. David Alan Gilbert
@ 2019-08-07 0:14 ` Wei Yang
0 siblings, 0 replies; 7+ messages in thread
From: Wei Yang @ 2019-08-07 0:14 UTC (permalink / raw)
To: Dr. David Alan Gilbert; +Cc: quintela, Wei Yang, qemu-devel
On Tue, Aug 06, 2019 at 03:51:17PM +0100, Dr. David Alan Gilbert wrote:
>* Wei Yang (richardw.yang@linux.intel.com) wrote:
>> The purpose of the calculation is to find a HostPage which is partially
>> dirty.
>>
>> * fixup_start_addr points to the start of the HostPage to discard
>> * run_start points to the next HostPage to check
>>
>> While in the middle stage, there would two cases for run_start:
>>
>> * aligned with HostPage means this is not partially dirty
>> * not aligned means this is partially dirty
>>
>> When it is aligned, no work and calculation is necessary. run_start
>> already points to the start of next HostPage and is ready to continue.
>>
>> When it is not aligned, the calculation could be simplified with:
>>
>> * fixup_start_addr = QEMU_ALIGN_DOWN(run_start, host_ratio)
>> * run_start = QEMU_ALIGN_UP(run_start, host_ratio)
>>
>> By doing so, run_start always points to the next HostPage to check.
>> fixup_start_addr always points to the HostPage to discard.
>>
>> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
>
>Yes that's a lot shorter; note it doess it on top of your cleanup
>from a couple of weeks back.
>
You are right, I forget to mention it :-)
>Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
>
>
>> ---
>> migration/ram.c | 34 +++++++---------------------------
>> 1 file changed, 7 insertions(+), 27 deletions(-)
>>
>> diff --git a/migration/ram.c b/migration/ram.c
>> index c9585487ac..d86661a015 100644
>> --- a/migration/ram.c
>> +++ b/migration/ram.c
>> @@ -2956,7 +2956,6 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
>> }
>>
>> while (run_start < pages) {
>> - unsigned long fixup_start_addr;
>> unsigned long host_offset;
>>
>> /*
>> @@ -2964,45 +2963,26 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
>> * page, then we need to fixup this host page.
>> */
>> host_offset = run_start % host_ratio;
>> - if (host_offset) {
>> - fixup_start_addr = run_start - host_offset;
>> - /*
>> - * This host page has gone, the next loop iteration starts
>> - * from after the fixup
>> - */
>> - run_start = fixup_start_addr + host_ratio;
>> - } else {
>> + if (!host_offset) {
>> /* Find the end of this run */
>> - unsigned long run_end;
>> if (unsent_pass) {
>> - run_end = find_next_bit(unsentmap, pages, run_start + 1);
>> + run_start = find_next_bit(unsentmap, pages, run_start + 1);
>> } else {
>> - run_end = find_next_zero_bit(bitmap, pages, run_start + 1);
>> + run_start = find_next_zero_bit(bitmap, pages, run_start + 1);
>> }
>> /*
>> * If the end isn't at the start of a host page, then the
>> * run doesn't finish at the end of a host page
>> * and we need to discard.
>> */
>> - host_offset = run_end % host_ratio;
>> - if (host_offset) {
>> - fixup_start_addr = run_end - host_offset;
>> - /*
>> - * This host page has gone, the next loop iteration starts
>> - * from after the fixup
>> - */
>> - run_start = fixup_start_addr + host_ratio;
>> - } else {
>> - /*
>> - * No discards on this iteration, next loop starts from
>> - * next sent/dirty page
>> - */
>> - run_start = run_end + 1;
>> - }
>> + host_offset = run_start % host_ratio;
>> }
>>
>> if (host_offset) {
>> unsigned long page;
>> + unsigned long fixup_start_addr = QEMU_ALIGN_DOWN(run_start,
>> + host_ratio);
>> + run_start = QEMU_ALIGN_UP(run_start, host_ratio);
>>
>> /* Tell the destination to discard this page */
>> if (unsent_pass || !test_bit(fixup_start_addr, unsentmap)) {
>> --
>> 2.17.1
>>
>--
>Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
--
Wei Yang
Help you, Help me
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Qemu-devel] [PATCH 0/2] migration/postcopy: simplify postcopy_chunk_hostpages_pass
2019-08-06 0:46 [Qemu-devel] [PATCH 0/2] migration/postcopy: simplify postcopy_chunk_hostpages_pass Wei Yang
2019-08-06 0:46 ` [Qemu-devel] [PATCH 1/2] migration/postcopy: simplify calculation of run_start and fixup_start_addr Wei Yang
2019-08-06 0:46 ` [Qemu-devel] [PATCH 2/2] migration/postcopy: use QEMU_IS_ALIGNED to replace host_offset Wei Yang
@ 2019-08-07 18:43 ` Dr. David Alan Gilbert
2 siblings, 0 replies; 7+ messages in thread
From: Dr. David Alan Gilbert @ 2019-08-07 18:43 UTC (permalink / raw)
To: Wei Yang; +Cc: qemu-devel, quintela
* Wei Yang (richardw.yang@linux.intel.com) wrote:
> When looking into function postcopy_chunk_hostpages_pass(), we could use
> alignment calculation to simplify it.
>
> Wei Yang (2):
> migration/postcopy: simplify calculation of run_start and
> fixup_start_addr
> migration/postcopy: use QEMU_IS_ALIGNED to replace host_offset
>
> migration/ram.c | 37 +++++++------------------------------
> 1 file changed, 7 insertions(+), 30 deletions(-)
Queued
> --
> 2.17.1
>
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2019-08-07 18:44 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2019-08-06 0:46 [Qemu-devel] [PATCH 0/2] migration/postcopy: simplify postcopy_chunk_hostpages_pass Wei Yang
2019-08-06 0:46 ` [Qemu-devel] [PATCH 1/2] migration/postcopy: simplify calculation of run_start and fixup_start_addr Wei Yang
2019-08-06 14:51 ` Dr. David Alan Gilbert
2019-08-07 0:14 ` Wei Yang
2019-08-06 0:46 ` [Qemu-devel] [PATCH 2/2] migration/postcopy: use QEMU_IS_ALIGNED to replace host_offset Wei Yang
2019-08-06 15:47 ` Dr. David Alan Gilbert
2019-08-07 18:43 ` [Qemu-devel] [PATCH 0/2] migration/postcopy: simplify postcopy_chunk_hostpages_pass Dr. David Alan Gilbert
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