[CRIU] [PATCH RFC 0/2] page-read: use in-memory PagemapEntry's

[Mike Rapoport]

On Mon, Jun 13, 2016 at 12:29 PM, Mike Rapoport <rppt at linux.vnet.ibm.com> wrote:
>> >
>> > Except the close part :)
>>
>> Would you send an incremental patch doing this, please?
>
> Found off-by-one in pme index calculations...
> Resending the entire patch.

Ping?

> From 7a7c93ff096355feacd7a486769c4f7d2d36e430 Mon Sep 17 00:00:00 2001
> From: Mike Rapoport <rppt at linux.vnet.ibm.com>
> Date: Thu, 2 Jun 2016 15:25:41 +0300
> Subject: [CRIU][PATCH v2 2/2] criu: page-read: read pagemaps at open time and
>  keep them in memory
>
> Signed-off-by: Mike Rapoport <rppt at linux.vnet.ibm.com>
> ---
>  criu/include/page-read.h |  4 +++
>  criu/page-read.c         | 85 ++++++++++++++++++++++++++++++++++++++++++++----
>  2 files changed, 83 insertions(+), 6 deletions(-)
>
> diff --git a/criu/include/page-read.h b/criu/include/page-read.h
> index 4b6b5b7..4c6d21e 100644
> --- a/criu/include/page-read.h
> +++ b/criu/include/page-read.h
> @@ -68,6 +68,10 @@ struct page_read {
>         struct iovec bunch;             /* record consequent neighbour
>                                            iovecs to punch together */
>         unsigned id; /* for logging */
> +
> +       PagemapEntry **pmes;
> +       int nr_pmes;
> +       int curr_pme;
>  };
>
>  #define PR_SHMEM       0x1
> diff --git a/criu/page-read.c b/criu/page-read.c
> index 933f047..f06b11f 100644
> --- a/criu/page-read.c
> +++ b/criu/page-read.c
> @@ -59,12 +59,12 @@ void iovec2pagemap(struct iovec *iov, PagemapEntry *pe)
>
>  static int get_pagemap(struct page_read *pr, struct iovec *iov)
>  {
> -       int ret;
>         PagemapEntry *pe;
>
> -       ret = pb_read_one_eof(pr->pmi, &pe, PB_PAGEMAP);
> -       if (ret <= 0)
> -               return ret;
> +       if (pr->curr_pme >= pr->nr_pmes)
> +               return 0;
> +
> +       pe = pr->pmes[pr->curr_pme];
>
>         pagemap2iovec(pe, iov);
>
> @@ -81,7 +81,7 @@ static int get_pagemap(struct page_read *pr, struct iovec *iov)
>
>  static void put_pagemap(struct page_read *pr)
>  {
> -       pagemap_entry__free_unpacked(pr->pe, NULL);
> +       pr->curr_pme++;
>  }
>
>  static void skip_pagemap_pages(struct page_read *pr, unsigned long len)
> @@ -216,6 +216,16 @@ static int read_pagemap_page(struct page_read *pr, unsigned long vaddr, int nr,
>         return 1;
>  }
>
> +static void free_pagemaps(struct page_read *pr)
> +{
> +       int i;
> +
> +       for (i = 0; i < pr->nr_pmes; i++)
> +               pagemap_entry__free_unpacked(pr->pmes[i], NULL);
> +
> +       xfree(pr->pmes);
> +}
> +
>  static void close_page_read(struct page_read *pr)
>  {
>         int ret;
> @@ -233,9 +243,13 @@ static void close_page_read(struct page_read *pr)
>                 xfree(pr->parent);
>         }
>
> -       close_image(pr->pmi);
> +       if (pr->pmi)
> +               close_image(pr->pmi);
>         if (pr->pi)
>                 close_image(pr->pi);
> +
> +       if (pr->pmes)
> +               free_pagemaps(pr);
>  }
>
>  static int try_open_parent(int dfd, int pid, struct page_read *pr, int pr_flags)
> @@ -272,6 +286,60 @@ err_cl:
>         return -1;
>  }
>
> +/*
> + * The pagemap entry size is at least 8 bytes for small mappings with
> + * low address and may get to 18 bytes or even more for large mappings
> + * with high address and in_parent flag set. 16 seems to be nice round
> + * number to minimize {over,under}-allocations
> + */
> +#define PAGEMAP_ENTRY_SIZE_ESTIMATE 16
> +
> +static int init_pagemaps(struct page_read *pr)
> +{
> +       off_t fsize;
> +       int nr_pmes, nr_realloc;
> +
> +       fsize = img_raw_size(pr->pmi);
> +       if (fsize < 0)
> +               return -1;
> +
> +       nr_pmes = fsize / PAGEMAP_ENTRY_SIZE_ESTIMATE + 1;
> +       nr_realloc = nr_pmes / 2;
> +
> +       pr->pmes = xzalloc(nr_pmes * sizeof(*pr->pmes));
> +       if (!pr->pmes)
> +               return -1;
> +
> +       pr->nr_pmes = pr->curr_pme = 0;
> +
> +       while (1) {
> +               int ret = pb_read_one_eof(pr->pmi, &pr->pmes[pr->nr_pmes],
> +                                         PB_PAGEMAP);
> +               if (ret < 0)
> +                       goto free_pagemaps;
> +               if (ret == 0)
> +                       break;
> +
> +               pr->nr_pmes++;
> +               if (pr->nr_pmes >= nr_pmes) {
> +                       nr_pmes += nr_realloc;
> +                       pr->pmes = xrealloc(pr->pmes,
> +                                           nr_pmes * sizeof(*pr->pmes));
> +                       if (!pr->pmes)
> +                               goto free_pagemaps;
> +               }
> +       }
> +
> +       return 0;
> +
> +       close_image(pr->pmi);
> +       pr->pmi = NULL;
> +
> +free_pagemaps:
> +       free_pagemaps(pr);
> +       return -1;
> +}
> +
>  int open_page_read_at(int dfd, int pid, struct page_read *pr, int pr_flags)
>  {
>         int flags, i_typ, i_typ_o;
> @@ -323,6 +391,11 @@ int open_page_read_at(int dfd, int pid, struct page_read *pr, int pr_flags)
>                 return -1;
>         }
>
> +       if (init_pagemaps(pr)) {
> +               close_page_read(pr);
> +               return -1;
> +       }
> +
>         pr->get_pagemap = get_pagemap;
>         pr->put_pagemap = put_pagemap;
>         pr->read_pages = read_pagemap_page;
> --
> 1.9.1
>



-- 
Sincerely yours,
Mike.