Re: [PATCH 1/2] intel_get_llc_size: Small tool to query LLC size

Ben Widawsky
2013-07-12T17:50:22Z

On Fri, Jul 12, 2013 at 10:39:51AM -0700, Chad Versace wrote:
> On 07/11/2013 11:53 AM, Ben Widawsky wrote:
> >v2: Use the new param
> >
> >CC: Chad Versace <chad.versace@linux.intel.com>
> >CC: Bryan Bell <bryan.j.bell@intel.com>
> >Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> >---
> > tools/Makefile.am | 1 +
> > tools/intel_get_llc_size.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 59 insertions(+)
> > create mode 100644 tools/intel_get_llc_size.c
> >
> >diff --git a/tools/Makefile.am b/tools/Makefile.am
> >index 2519169..a064b65 100644
> >--- a/tools/Makefile.am
> >+++ b/tools/Makefile.am
> >@@ -9,6 +9,7 @@ bin_PROGRAMS = \
> > intel_bios_dumper \
> > intel_bios_reader \
> > intel_error_decode \
> >+ intel_get_llc_size \
> > intel_gpu_top \
> > intel_gpu_time \
> > intel_gtt \
> >diff --git a/tools/intel_get_llc_size.c b/tools/intel_get_llc_size.c
> >new file mode 100644
> >index 0000000..498e252
> >--- /dev/null
> >+++ b/tools/intel_get_llc_size.c
> >@@ -0,0 +1,58 @@
> >+/*
> >+ * Copyright © 2013 Intel Corporation
> >+ *
> >+ * Permission is hereby granted, free of charge, to any person obtaining a
> >+ * copy of this software and associated documentation files (the "Software"),
> >+ * to deal in the Software without restriction, including without limitation
> >+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> >+ * and/or sell copies of the Software, and to permit persons to whom the
> >+ * Software is furnished to do so, subject to the following conditions:
> >+ *
> >+ * The above copyright notice and this permission notice (including the next
> >+ * paragraph) shall be included in all copies or substantial portions of the
> >+ * Software.
> >+ *
> >+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> >+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> >+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> >+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> >+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> >+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
> >+ * DEALINGS IN THE SOFTWARE.
> >+ *
> >+ */
> >+
> >+#include <sys/ioctl.h>
> >+#include "drmtest.h"
> >+#include "i915_drm.h"
> >+
> >+#define LOCAL__I915_PARAM_LLC_SIZE 27
> >+static int get_llc_size(int fd)
> >+{
> >+ struct drm_i915_getparam gp;
> >+ int size;
> >+
> >+ gp.param = LOCAL__I915_PARAM_LLC_SIZE;
> >+ gp.value = &size;
> >+
> >+ if (ioctl(fd, DRM_IOCTL_I915_GETPARAM, &gp, sizeof(gp)))
> >+ return 0;
> >+
> >+ return size;
> >+}
> >+
> >+int main(int argc, char **argv)
> >+{
> >+ int size, fd = drm_open_any();
> >+
> >+ size = get_llc_size(fd);
> >+
> >+ if (size == 0)
> >+ fprintf(stdout, "Doesn't have LLC\n");
> >+ else if (size == 1)
> >+ fprintf(stdout, "Kernel is too old to determine LLC size\n");
> >+ else
> >+ fprintf(stdout, "LLC size = %dK\n", size>>10);
>
> This if-tree looks wrong. If the kernel doesn't know about I915_PARAM_LLC_SIZE,
> the ioctl returns -1, and get_llc_size() returns 0, and the if-tree prints the
> wrong error.
>
> How about making get_llc_size() return -1 on error? Or am I missing something here?
>

Looks like the tool needed updating after the last param change and I
missed it. It should have been correct before (though in the case of no
HAS_LLC param it was also bad). Your suggestion is the right thing to do.

If Daniel decides to merge the kernel patch, I will fix this.

>
> >+
> >+ return 0;
> >+}
> >
>
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--
Ben Widawsky, Intel Open Source Technology Center
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