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Re: [PATCH RFC 06/15] migration: Move temp page setup and cleanup into s
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [PATCH RFC 06/15] migration: Move temp page setup and cleanup into separate functions |
Date: |
Wed, 19 Jan 2022 16:58:32 +0000 |
User-agent: |
Mutt/2.1.5 (2021-12-30) |
* Peter Xu (peterx@redhat.com) wrote:
> Temp pages will need to grow if we want to have multiple channels for
> postcopy,
> because each channel will need its own temp page to cache huge page data.
>
> Before doing that, cleanup the related code. No functional change intended.
>
> Since at it, touch up the errno handling a little bit on the setup side.
>
> Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
> migration/postcopy-ram.c | 82 +++++++++++++++++++++++++---------------
> 1 file changed, 51 insertions(+), 31 deletions(-)
>
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index 2176ed68a5..e662dd05cc 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -523,6 +523,19 @@ int postcopy_ram_incoming_init(MigrationIncomingState
> *mis)
> return 0;
> }
>
> +static void postcopy_temp_pages_cleanup(MigrationIncomingState *mis)
> +{
> + if (mis->postcopy_tmp_page) {
> + munmap(mis->postcopy_tmp_page, mis->largest_page_size);
> + mis->postcopy_tmp_page = NULL;
> + }
> +
> + if (mis->postcopy_tmp_zero_page) {
> + munmap(mis->postcopy_tmp_zero_page, mis->largest_page_size);
> + mis->postcopy_tmp_zero_page = NULL;
> + }
> +}
> +
> /*
> * At the end of a migration where postcopy_ram_incoming_init was called.
> */
> @@ -564,14 +577,8 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState
> *mis)
> }
> }
>
> - if (mis->postcopy_tmp_page) {
> - munmap(mis->postcopy_tmp_page, mis->largest_page_size);
> - mis->postcopy_tmp_page = NULL;
> - }
> - if (mis->postcopy_tmp_zero_page) {
> - munmap(mis->postcopy_tmp_zero_page, mis->largest_page_size);
> - mis->postcopy_tmp_zero_page = NULL;
> - }
> + postcopy_temp_pages_cleanup(mis);
> +
> trace_postcopy_ram_incoming_cleanup_blocktime(
> get_postcopy_total_blocktime());
>
> @@ -1082,6 +1089,40 @@ retry:
> return NULL;
> }
>
> +static int postcopy_temp_pages_setup(MigrationIncomingState *mis)
> +{
> + int err;
> +
> + mis->postcopy_tmp_page = mmap(NULL, mis->largest_page_size,
> + PROT_READ | PROT_WRITE,
> + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> + if (mis->postcopy_tmp_page == MAP_FAILED) {
> + err = errno;
> + mis->postcopy_tmp_page = NULL;
> + error_report("%s: Failed to map postcopy_tmp_page %s",
> + __func__, strerror(err));
> + return -err;
> + }
> +
> + /*
> + * 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) {
> + err = errno;
> + mis->postcopy_tmp_zero_page = NULL;
> + error_report("%s: Failed to map large zero page %s",
> + __func__, strerror(err));
> + return -err;
> + }
> +
> + memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
> +
> + return 0;
> +}
> +
> int postcopy_ram_incoming_setup(MigrationIncomingState *mis)
> {
> /* Open the fd for the kernel to give us userfaults */
> @@ -1122,32 +1163,11 @@ int
> postcopy_ram_incoming_setup(MigrationIncomingState *mis)
> return -1;
> }
>
> - mis->postcopy_tmp_page = mmap(NULL, mis->largest_page_size,
> - PROT_READ | PROT_WRITE, MAP_PRIVATE |
> - MAP_ANONYMOUS, -1, 0);
> - if (mis->postcopy_tmp_page == MAP_FAILED) {
> - mis->postcopy_tmp_page = NULL;
> - error_report("%s: Failed to map postcopy_tmp_page %s",
> - __func__, strerror(errno));
> + if (postcopy_temp_pages_setup(mis)) {
> + /* Error dumped in the sub-function */
> 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);
> -
> trace_postcopy_ram_enable_notify();
>
> return 0;
> --
> 2.32.0
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
- Re: [PATCH RFC 02/15] migration: Allow pss->page jump over clean pages, (continued)
- [PATCH RFC 06/15] migration: Move temp page setup and cleanup into separate functions, Peter Xu, 2022/01/19
- [PATCH RFC 07/15] migration: Introduce postcopy channels on dest node, Peter Xu, 2022/01/19
- [PATCH RFC 08/15] migration: Dump ramblock and offset too when non-same-page detected, Peter Xu, 2022/01/19
- [PATCH RFC 09/15] migration: Add postcopy_thread_create(), Peter Xu, 2022/01/19
- [PATCH RFC 10/15] migration: Move static var in ram_block_from_stream() into global, Peter Xu, 2022/01/19
- [PATCH RFC 11/15] migration: Add pss.postcopy_requested status, Peter Xu, 2022/01/19
- [PATCH RFC 12/15] migration: Move migrate_allow_multifd and helpers into migration.c, Peter Xu, 2022/01/19
- [PATCH RFC 13/15] migration: Add postcopy-preempt capability, Peter Xu, 2022/01/19
- [PATCH RFC 15/15] tests: Add postcopy preempt test, Peter Xu, 2022/01/19
- [PATCH RFC 14/15] migration: Postcopy preemption on separate channel, Peter Xu, 2022/01/19