Re: [Xen-devel] [PATCH 1/1] xen: move TLB-flush filtering out into populate_physmap

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Sep 06, 2016 at 01:17:38PM +0800, Dongli Zhang wrote:
> This patch implemented parts of TODO left in commit id
> a902c12ee45fc9389eb8fe54eeddaf267a555c58. It moved TLB-flush filtering out
> into populate_physmap.
> 
> Because of TLB-flush in alloc_heap_pages, it's very slow to create a guest
> with memory size of more than 100GB on host with 100+ cpus.
> 
> This patch introduced a "MEMF_no_tlbflush" bit to memflag to indicate
> whether TLB-flush should be done in alloc_heap_pages or its caller
> populate_physmap.  Once this bit is set in memflag, alloc_heap_pages will
> ignore TLB-flush.
> 
> Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
> ---
>  xen/common/memory.c     | 26 ++++++++++++++++++++++++++
>  xen/common/page_alloc.c |  3 ++-
>  xen/include/xen/mm.h    |  2 ++
>  3 files changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/common/memory.c b/xen/common/memory.c
> index f34dd56..14ec5fa 100644
> --- a/xen/common/memory.c
> +++ b/xen/common/memory.c
> @@ -141,6 +141,8 @@ static void populate_physmap(struct memop_args *a)
>      unsigned int i, j;
>      xen_pfn_t gpfn, mfn;
>      struct domain *d = a->domain, *curr_d = current->domain;
> +     bool_t need_tlbflush = 0;
> +     uint32_t tlbflush_timestamp = 0;
>  
>      if ( !guest_handle_subrange_okay(a->extent_list, a->nr_done,
>                                       a->nr_extents-1) )
> @@ -149,6 +151,8 @@ static void populate_physmap(struct memop_args *a)
>      if ( a->extent_order > (a->memflags & MEMF_populate_on_demand ? 
> MAX_ORDER :
>                              max_order(curr_d)) )
>          return;
> +     
> +     a->memflags |= MEMF_no_tlbflush;
>  
>      for ( i = a->nr_done; i < a->nr_extents; i++ )
>      {
> @@ -213,6 +217,18 @@ static void populate_physmap(struct memop_args *a)
>                                   i, a->nr_extents);
>                      goto out;
>                  }
> +                             
> +                             for ( j = 0; j < (1U << a->extent_order); j++ )
> +                             {
> +                                     if ( page[j].u.free.need_tlbflush &&
> +                                              (page[j].tlbflush_timestamp <= 
> tlbflush_current_time()) &&
> +                                              (!need_tlbflush ||
> +                                               (page[j].tlbflush_timestamp > 
> tlbflush_timestamp)) )
> +                                     {
> +                                             need_tlbflush = 1;
> +                                             tlbflush_timestamp = 
> page[j].tlbflush_timestamp;
> +                                     }
> +                             }
>  

Indentation seems rather wrong.

Please configure your editor properly.

Wei.

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