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Re: [Xen-devel] [PATCH v3 11/14] libxl: get and set soft affinity

On 11/18/2013 06:18 PM, Dario Faggioli wrote:
Make space for two new cpumap-s, one in vcpu_info (for getting
soft affinity) and build_info (for setting it). Provide two
new API calls:

  * libxl_set_vcpuaffinity2, taking a cpumap and setting either
    hard, soft or both affinity to it, depending on 'flags';
  * libxl_set_vcpuaffinity3, taking two cpumap, one for hard
    and one for soft affinity.

The bheavior of the existing libxl_set_vcpuaffinity is left
unchanged, i.e., it only set hard affinity.

Getting soft affinity happens indirectly, via `xl vcpu-list'
(as it is already for hard affinity).

The new calls include logic to check whether the affinity which
will be used by Xen to schedule the vCPU(s) does actually match
with the cpumap provided. In fact, we want to allow every possible
combination of hard and soft affinities to be set, but we warn
the user upon particularly weird combinations (e.g., hard and
soft being disjoint sets of pCPUs).

Also, this is the first change breaking the libxl ABI, so it
bumps the MAJOR.

Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>

The interface is fine with me (I would probably just have 2 and not 3, but I'm OK with both). Just a few minor comments:

@@ -973,6 +987,22 @@ int libxl_set_vcpuaffinity(libxl_ctx *ctx, uint32_t domid, 
uint32_t vcpuid,
                             libxl_bitmap *cpumap);
  int libxl_set_vcpuaffinity_all(libxl_ctx *ctx, uint32_t domid,
                                 unsigned int max_vcpus, libxl_bitmap *cpumap);
+int libxl_set_vcpuaffinity2(libxl_ctx *ctx, uint32_t domid, uint32_t vcpuid,
+                            const libxl_bitmap *cpumap, int flags);
+int libxl_set_vcpuaffinity_all2(libxl_ctx *ctx, uint32_t domid,
+                                unsigned int max_vcpus,
+                                const libxl_bitmap *cpumap, int flags);

Should we have a bit more documentation about the behavior of "flags" somewhere?

diff --git a/tools/libxl/libxl_utils.h b/tools/libxl/libxl_utils.h
index b11cf28..fc3afee 100644
--- a/tools/libxl/libxl_utils.h
+++ b/tools/libxl/libxl_utils.h
@@ -98,6 +98,21 @@ static inline int libxl_bitmap_cpu_valid(libxl_bitmap 
*bitmap, int bit)
  #define libxl_for_each_set_bit(v, m) for (v = 0; v < (m).size * 8; v++) \
                                               if (libxl_bitmap_test(&(m), v))

+static inline int libxl_bitmap_equal(const libxl_bitmap *ba,
+                                     const libxl_bitmap *bb,
+                                     int nr_bits)
+    int i;
+    /* Only check nr_bits (all bits if <= 0) */
+    nr_bits = nr_bits <=0 ? ba->size * 8 : nr_bits;

The conditional should really have parenthesis around it, I'm pretty sure; and the spacing is inconsistent.


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