Re: [Xen-devel] [PATCH 2/2] tools: utility to dump guest grant table info

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Fri, Jun 30, 2017 at 03:21:31PM +0800, Dongli Zhang wrote:
> As both xen-netfront and xen-blkfront support multi-queue, they would
> consume a lot of grant table references when there are many paravirtual
> devices and vcpus assigned to guest. Guest domU might panic or hang due to
> grant allocation failure when nr_grant_frames in guest has reached its max
> value.
> 
> This utility would help the administrators to monitor the guest grant table
> frame usage on dom0 side so that it is not required to debug on guest
> kernel side for crash/hang analysis anymore.
> 
> Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
> ---
>  tools/misc/Makefile           |  4 ++++
>  tools/misc/xen-gnttab-query.c | 45 
> +++++++++++++++++++++++++++++++++++++++++++

Would this be better name 'xen-diag' or such? And in the future
more diagnostic pieces could be added in? For example I can see
parts of xen-hptool moving in there.

>  2 files changed, 49 insertions(+)
>  create mode 100644 tools/misc/xen-gnttab-query.c
> 
> diff --git a/tools/misc/Makefile b/tools/misc/Makefile
> index 8152f7b..d081b4b 100644
> --- a/tools/misc/Makefile
> +++ b/tools/misc/Makefile
> @@ -31,6 +31,7 @@ INSTALL_SBIN                   += xenperf
>  INSTALL_SBIN                   += xenpm
>  INSTALL_SBIN                   += xenwatchdogd
>  INSTALL_SBIN                   += xen-livepatch
> +INSTALL_SBIN                   += xen-gnttab-query
>  INSTALL_SBIN += $(INSTALL_SBIN-y)
>  
>  # Everything to be installed in a private bin/
> @@ -108,4 +109,7 @@ xen-lowmemd: xen-lowmemd.o
>  xencov: xencov.o
>       $(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) $(APPEND_LDFLAGS)
>  
> +xen-gnttab-query: xen-gnttab-query.o
> +     $(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) $(APPEND_LDFLAGS)
> +
>  -include $(DEPS)
> diff --git a/tools/misc/xen-gnttab-query.c b/tools/misc/xen-gnttab-query.c
> new file mode 100644
> index 0000000..3f93a6c
> --- /dev/null
> +++ b/tools/misc/xen-gnttab-query.c
> @@ -0,0 +1,45 @@

Please add Oracle's copyright (see the xen-livepatch.c for example).


> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <err.h>
> +#include <xenctrl.h>
> +
> +void show_help(void)
> +{
> +    fprintf(stderr,
> +            "xen-gnttab-query: query grant table info\n"
> +            "Usage: xen-gnttab-query [domid (default 0)]\n");
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +    xc_interface *xch;
> +    int domid, rc, c;
> +    struct gnttab_query_size query;
> +
> +    while ( (c = getopt(argc, argv, "h")) != -1 )
> +    {
> +        switch ( c )
> +        {
> +        case 'h':
> +            show_help();
> +            return 0;
> +        }
> +    }
> +
> +    domid = (argc > 1) ? strtol(argv[1], NULL, 10) : 0;
> +
> +    xch = xc_interface_open(0, 0, 0);
> +    if ( !xch )
> +        errx(1, "failed to open control interface");
> +
> +    query.dom = domid;
> +    rc = xc_gnttab_query_size(xch, &query);
> +
> +    if ( rc == 0 && (query.status == GNTST_okay) )
> +        printf("domid=%d: nr_frames=%d, max_nr_frames=%d\n",
> +               query.dom, query.nr_frames, query.max_nr_frames);
> +
> +    xc_interface_close(xch);
> +
> +    return 0;
> +}
> -- 
> 2.7.4
> 
> 
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