linux-kernel - Re: [PATCH v5 5/5] KVM: selftests: Run dirty_log_perf

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Message-ID: <Y1HAuDAP66HNk1rT@google.com>
Date:   Thu, 20 Oct 2022 21:42:16 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Vipin Sharma <vipinsh@...gle.com>
Cc:     pbonzini@...hat.com, dmatlack@...gle.com, andrew.jones@...ux.dev,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 5/5] KVM: selftests: Run dirty_log_perf_test on
 specific CPUs

On Mon, Oct 10, 2022, Vipin Sharma wrote:
> @@ -383,6 +383,18 @@ static void help(char *name)
>  	backing_src_help("-s");
>  	printf(" -x: Split the memory region into this number of memslots.\n"
>  	       "     (default: 1)\n");
> +	printf(" -c: Pin tasks to physical CPUs.  Takes a list of comma separated\n"
> +	       "     values (target pCPU), one for each vCPU, plus an optional\n"
> +	       "     entry for the main application task (specified via entry\n"
> +	       "     <nr_vcpus + 1>).  If used, entries must be provided for all\n"
> +	       "     vCPUs, i.e. pinning vCPUs is all or nothing.\n\n"
> +	       "     Example: ./dirty_log_perf_test -v 3 -c 22,23,24,50\n"
> +	       "     will create 3 vCPUs, and pin vCPU0=>pCPU22, vCPU1=>pCPU23\n"
> +	       "     vCPU2=>pCPU24, and pin the application task to pCPU50.\n"
> +	       "     To leave the application task unpinned, drop the final\n"
> +	       "     entry:\n"
> +	       "       ./dirty_log_perf_test -v 3 -c 22,23,24\n\n"
> +	       "     (default: no pinning)\n");

Any objection to tweaking the formatting to make the output easier to parse?  And
to match the indentation used by guest_modes_help().  E.g. This

	printf(" -c: Pin tasks to physical CPUs.  Takes a list of comma separated\n"
	       "     values (target pCPU), one for each vCPU, plus an optional\n"
	       "     entry for the main application task (specified via entry\n"
	       "     <nr_vcpus + 1>).  If used, entries must be provided for all\n"
	       "     vCPUs, i.e. pinning vCPUs is all or nothing.\n\n"
	       "     E.g. to create 3 vCPUs, pin vCPU0=>pCPU22, vCPU1=>pCPU23\n"
	       "     vCPU2=>pCPU24, and pin the application task to pCPU50:\n\n"
	       "         ./dirty_log_perf_test -v 3 -c 22,23,24,50\n\n"
	       "     To leave the application task unpinned, drop the final entry:\n\n"
	       "         ./dirty_log_perf_test -v 3 -c 22,23,24\n\n"
	       "     (default: no pinning)\n");

yields:

 -c: Pin tasks to physical CPUs.  Takes a list of comma separated
     values (target pCPU), one for each vCPU, plus an optional
     entry for the main application task (specified via entry
     <nr_vcpus + 1>).  If used, entries must be provided for all
     vCPUs, i.e. pinning vCPUs is all or nothing.

     E.g. to create 3 vCPUs, pin vCPU0=>pCPU22, vCPU1=>pCPU23
     vCPU2=>pCPU24, and pin the application task to pCPU50:

         ./dirty_log_perf_test -v 3 -c 22,23,24,50

     To leave the application task unpinned, drop the final entry:

         ./dirty_log_perf_test -v 3 -c 22,23,24

     (default: no pinning)


versus:

 -c: Pin tasks to physical CPUs.  Takes a list of comma separated
     values (target pCPU), one for each vCPU, plus an optional
     entry for the main application task (specified via entry
     <nr_vcpus + 1>).  If used, entries must be provided for all
     vCPUs, i.e. pinning vCPUs is all or nothing.

     Example: ./dirty_log_perf_test -v 3 -c 22,23,24,50
     will create 3 vCPUs, and pin vCPU0=>pCPU22, vCPU1=>pCPU23
     vCPU2=>pCPU24, and pin the application task to pCPU50.
     To leave the application task unpinned, drop the final
     entry:
       ./dirty_log_perf_test -v 3 -c 22,23,24

     (default: no pinning)