postcopy_ram_incoming_setup() and postcopy_ram_incoming_cleanup() are
counterpart. It is reasonable to map/unmap large zero page in these two
functions respectively.
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
---
migration/postcopy-ram.c | 34 +++++++++++++++++-----------------
1 file changed, 17 insertions(+), 17 deletions(-)
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index e554f93eec..813cfa5c42 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -1142,6 +1142,22 @@ int postcopy_ram_incoming_setup(MigrationIncomingState *mis)
return -1;
}
+ /*
+ * Map large zero page when kernel can't use UFFDIO_ZEROPAGE for hugepages
+ */
+ mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS,
+ -1, 0);
+ if (mis->postcopy_tmp_zero_page == MAP_FAILED) {
+ int e = errno;
+ mis->postcopy_tmp_zero_page = NULL;
+ error_report("%s: Failed to map large zero page %s",
+ __func__, strerror(e));
+ return -e;
+ }
+ memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
+
/*
* Ballooning can mark pages as absent while we're postcopying
* that would cause false userfaults.
@@ -1248,23 +1264,7 @@ int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
qemu_ram_block_host_offset(rb,
host));
} else {
- /* The kernel can't use UFFDIO_ZEROPAGE for hugepages */
- if (!mis->postcopy_tmp_zero_page) {
- mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size,
- PROT_READ | PROT_WRITE,
- MAP_PRIVATE | MAP_ANONYMOUS,
- -1, 0);
- if (mis->postcopy_tmp_zero_page == MAP_FAILED) {
- int e = errno;
- mis->postcopy_tmp_zero_page = NULL;
- error_report("%s: %s mapping large zero page",
- __func__, strerror(e));
- return -e;
- }
- memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
- }
- return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page,
- rb);
+ return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page, rb);
}
}
--
2.17.1
* Wei Yang (richardw.yang@linux.intel.com) wrote:
> postcopy_ram_incoming_setup() and postcopy_ram_incoming_cleanup() are
> counterpart. It is reasonable to map/unmap large zero page in these two
> functions respectively.
>
> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Yes, OK.
> ---
> migration/postcopy-ram.c | 34 +++++++++++++++++-----------------
> 1 file changed, 17 insertions(+), 17 deletions(-)
>
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index e554f93eec..813cfa5c42 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -1142,6 +1142,22 @@ int postcopy_ram_incoming_setup(MigrationIncomingState *mis)
> return -1;
> }
>
> + /*
> + * Map large zero page when kernel can't use UFFDIO_ZEROPAGE for hugepages
> + */
> + mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size,
> + PROT_READ | PROT_WRITE,
> + MAP_PRIVATE | MAP_ANONYMOUS,
> + -1, 0);
> + if (mis->postcopy_tmp_zero_page == MAP_FAILED) {
> + int e = errno;
> + mis->postcopy_tmp_zero_page = NULL;
> + error_report("%s: Failed to map large zero page %s",
> + __func__, strerror(e));
> + return -e;
Note this starts returning -errno where the rest of this function
returns 0 or -1; returning -errno is a good thing I think and it might
be good to change the other returns.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> + }
> + memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
> +
> /*
> * Ballooning can mark pages as absent while we're postcopying
> * that would cause false userfaults.
> @@ -1248,23 +1264,7 @@ int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
> qemu_ram_block_host_offset(rb,
> host));
> } else {
> - /* The kernel can't use UFFDIO_ZEROPAGE for hugepages */
> - if (!mis->postcopy_tmp_zero_page) {
> - mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size,
> - PROT_READ | PROT_WRITE,
> - MAP_PRIVATE | MAP_ANONYMOUS,
> - -1, 0);
> - if (mis->postcopy_tmp_zero_page == MAP_FAILED) {
> - int e = errno;
> - mis->postcopy_tmp_zero_page = NULL;
> - error_report("%s: %s mapping large zero page",
> - __func__, strerror(e));
> - return -e;
> - }
> - memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
> - }
> - return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page,
> - rb);
> + return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page, rb);
> }
> }
>
> --
> 2.17.1
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
On Tue, Oct 08, 2019 at 06:24:23PM +0100, Dr. David Alan Gilbert wrote:
>* Wei Yang (richardw.yang@linux.intel.com) wrote:
>> postcopy_ram_incoming_setup() and postcopy_ram_incoming_cleanup() are
>> counterpart. It is reasonable to map/unmap large zero page in these two
>> functions respectively.
>>
>> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
>
>Yes, OK.
>
>> ---
>> migration/postcopy-ram.c | 34 +++++++++++++++++-----------------
>> 1 file changed, 17 insertions(+), 17 deletions(-)
>>
>> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
>> index e554f93eec..813cfa5c42 100644
>> --- a/migration/postcopy-ram.c
>> +++ b/migration/postcopy-ram.c
>> @@ -1142,6 +1142,22 @@ int postcopy_ram_incoming_setup(MigrationIncomingState *mis)
>> return -1;
>> }
>>
>> + /*
>> + * Map large zero page when kernel can't use UFFDIO_ZEROPAGE for hugepages
>> + */
>> + mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size,
>> + PROT_READ | PROT_WRITE,
>> + MAP_PRIVATE | MAP_ANONYMOUS,
>> + -1, 0);
>> + if (mis->postcopy_tmp_zero_page == MAP_FAILED) {
>> + int e = errno;
>> + mis->postcopy_tmp_zero_page = NULL;
>> + error_report("%s: Failed to map large zero page %s",
>> + __func__, strerror(e));
>> + return -e;
>
>Note this starts returning -errno where the rest of this function
>returns 0 or -1; returning -errno is a good thing I think and it might
>be good to change the other returns.
>
This is reasonable, while I am thinking how caller would handle this.
For example, the return value would be finally returned to
qemu_loadvm_state_main(). If we handle each errno respectively in this
function, the code would be difficult to read and maintain.
Would it be good to classify return value to different category? Like
POSTCOPY_FATAL
POSTCOPY_RETRY
POSTCOPY_DISABLE
>
>Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
>
>> + }
>> + memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
>> +
>> /*
>> * Ballooning can mark pages as absent while we're postcopying
>> * that would cause false userfaults.
>> @@ -1248,23 +1264,7 @@ int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
>> qemu_ram_block_host_offset(rb,
>> host));
>> } else {
>> - /* The kernel can't use UFFDIO_ZEROPAGE for hugepages */
>> - if (!mis->postcopy_tmp_zero_page) {
>> - mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size,
>> - PROT_READ | PROT_WRITE,
>> - MAP_PRIVATE | MAP_ANONYMOUS,
>> - -1, 0);
>> - if (mis->postcopy_tmp_zero_page == MAP_FAILED) {
>> - int e = errno;
>> - mis->postcopy_tmp_zero_page = NULL;
>> - error_report("%s: %s mapping large zero page",
>> - __func__, strerror(e));
>> - return -e;
>> - }
>> - memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
>> - }
>> - return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page,
>> - rb);
>> + return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page, rb);
>> }
>> }
>>
>> --
>> 2.17.1
>>
>--
>Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
--
Wei Yang
Help you, Help me
* Wei Yang (richardw.yang@linux.intel.com) wrote:
> On Tue, Oct 08, 2019 at 06:24:23PM +0100, Dr. David Alan Gilbert wrote:
> >* Wei Yang (richardw.yang@linux.intel.com) wrote:
> >> postcopy_ram_incoming_setup() and postcopy_ram_incoming_cleanup() are
> >> counterpart. It is reasonable to map/unmap large zero page in these two
> >> functions respectively.
> >>
> >> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
> >
> >Yes, OK.
> >
> >> ---
> >> migration/postcopy-ram.c | 34 +++++++++++++++++-----------------
> >> 1 file changed, 17 insertions(+), 17 deletions(-)
> >>
> >> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> >> index e554f93eec..813cfa5c42 100644
> >> --- a/migration/postcopy-ram.c
> >> +++ b/migration/postcopy-ram.c
> >> @@ -1142,6 +1142,22 @@ int postcopy_ram_incoming_setup(MigrationIncomingState *mis)
> >> return -1;
> >> }
> >>
> >> + /*
> >> + * Map large zero page when kernel can't use UFFDIO_ZEROPAGE for hugepages
> >> + */
> >> + mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size,
> >> + PROT_READ | PROT_WRITE,
> >> + MAP_PRIVATE | MAP_ANONYMOUS,
> >> + -1, 0);
> >> + if (mis->postcopy_tmp_zero_page == MAP_FAILED) {
> >> + int e = errno;
> >> + mis->postcopy_tmp_zero_page = NULL;
> >> + error_report("%s: Failed to map large zero page %s",
> >> + __func__, strerror(e));
> >> + return -e;
> >
> >Note this starts returning -errno where the rest of this function
> >returns 0 or -1; returning -errno is a good thing I think and it might
> >be good to change the other returns.
> >
>
> This is reasonable, while I am thinking how caller would handle this.
>
> For example, the return value would be finally returned to
> qemu_loadvm_state_main(). If we handle each errno respectively in this
> function, the code would be difficult to read and maintain.
>
> Would it be good to classify return value to different category? Like
>
> POSTCOPY_FATAL
> POSTCOPY_RETRY
> POSTCOPY_DISABLE
It's actually quite difficult because unix errno's are too simple;
an EIO has too many causes.
ideally we'd like to be able to separate out a network transport error
that occurs during the postcopy phase for recovery and make sure
that we don't confuse that with any other error.
Dave
>
> >
> >Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> >
> >> + }
> >> + memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
> >> +
> >> /*
> >> * Ballooning can mark pages as absent while we're postcopying
> >> * that would cause false userfaults.
> >> @@ -1248,23 +1264,7 @@ int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
> >> qemu_ram_block_host_offset(rb,
> >> host));
> >> } else {
> >> - /* The kernel can't use UFFDIO_ZEROPAGE for hugepages */
> >> - if (!mis->postcopy_tmp_zero_page) {
> >> - mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size,
> >> - PROT_READ | PROT_WRITE,
> >> - MAP_PRIVATE | MAP_ANONYMOUS,
> >> - -1, 0);
> >> - if (mis->postcopy_tmp_zero_page == MAP_FAILED) {
> >> - int e = errno;
> >> - mis->postcopy_tmp_zero_page = NULL;
> >> - error_report("%s: %s mapping large zero page",
> >> - __func__, strerror(e));
> >> - return -e;
> >> - }
> >> - memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
> >> - }
> >> - return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page,
> >> - rb);
> >> + return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page, rb);
> >> }
> >> }
> >>
> >> --
> >> 2.17.1
> >>
> >--
> >Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
>
> --
> Wei Yang
> Help you, Help me
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
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