Re: [PATCH] sparc64: boot performance improvements

[Andrei Borzenkov]

On Tue, Oct 6, 2015 at 8:39 PM, Eric Snowberg <address@hidden> wrote:
> Keep of devices open.  This can save 6 - 7 seconds per open call and
> can decrease boot times from over 10 minutes to 29 seconds on
> larger SPARC systems.  The open/close calls with some vendors'
> SAS controllers cause the entire card to be reinitialized after
> each close.
>

Is it necessary to close these handles before launching kernel? It
sounds like it can accumulate quite a lot of them - are there any
memory limits/restrictions? Also your patch is rather generic and so
applies to any IEEE1275 platform, I think some of them may have less
resources. Just trying to understand what run-time cost is.

> Signed-off-by: Eric Snowberg <address@hidden>
> ---
>  grub-core/kern/ieee1275/ieee1275.c |   39 
> ++++++++++++++++++++++++++++++++++++
>  1 files changed, 39 insertions(+), 0 deletions(-)
>
> diff --git a/grub-core/kern/ieee1275/ieee1275.c 
> b/grub-core/kern/ieee1275/ieee1275.c
> index 9821702..30f973b 100644
> --- a/grub-core/kern/ieee1275/ieee1275.c
> +++ b/grub-core/kern/ieee1275/ieee1275.c
> @@ -19,11 +19,24 @@
>
>  #include <grub/ieee1275/ieee1275.h>
>  #include <grub/types.h>
> +#include <grub/misc.h>
> +#include <grub/list.h>
> +#include <grub/mm.h>
>
>  #define IEEE1275_PHANDLE_INVALID  ((grub_ieee1275_cell_t) -1)
>  #define IEEE1275_IHANDLE_INVALID  ((grub_ieee1275_cell_t) 0)
>  #define IEEE1275_CELL_INVALID     ((grub_ieee1275_cell_t) -1)
>
> +struct grub_of_opened_device
> +{
> +  struct grub_of_opened_device *next;
> +  struct grub_of_opened_device **prev;
> +  grub_ieee1275_ihandle_t ihandle;
> +  char *path;
> +};
> +
> +static struct grub_of_opened_device *grub_of_opened_devices;
> +
>
>
>  int
> @@ -452,6 +465,18 @@ grub_ieee1275_open (const char *path, 
> grub_ieee1275_ihandle_t *result)
>    }
>    args;
>
> +  struct grub_of_opened_device *dev;
> +
> +  FOR_LIST_ELEMENTS(dev, grub_of_opened_devices)
> +    if (grub_strcmp(dev->path, path) == 0)
> +      break;
> +
> +  if (dev)
> +  {
> +    *result = dev->ihandle;
> +    return 0;
> +  }
> +
>    INIT_IEEE1275_COMMON (&args.common, "open", 1, 1);
>    args.path = (grub_ieee1275_cell_t) path;
>
> @@ -460,6 +485,11 @@ grub_ieee1275_open (const char *path, 
> grub_ieee1275_ihandle_t *result)
>    *result = args.result;
>    if (args.result == IEEE1275_IHANDLE_INVALID)
>      return -1;
> +
> +  dev = grub_zalloc(sizeof(struct grub_of_opened_device));

Error check

> +  dev->path = grub_strdup(path);

Ditto

> +  dev->ihandle = args.result;
> +  grub_list_push(GRUB_AS_LIST_P (&grub_of_opened_devices), GRUB_AS_LIST 
> (dev));
>    return 0;
>  }
>
> @@ -473,6 +503,15 @@ grub_ieee1275_close (grub_ieee1275_ihandle_t ihandle)
>    }
>    args;
>
> +  struct grub_of_opened_device *dev;
> +
> +  FOR_LIST_ELEMENTS(dev, grub_of_opened_devices)
> +    if (dev->ihandle == ihandle)
> +      break;
> +
> +  if (dev)
> +    return 0;
> +

How can we come here (i.e. can we get open handle without grub_ieee1275_open)?

>    INIT_IEEE1275_COMMON (&args.common, "close", 1, 0);
>    args.ihandle = ihandle;
>
> --
> 1.7.1
>
>
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