)]}'
{
  "commit": "7ea5906405a1f3fc1c0033dfd7e02f2cfd1de5e5",
  "tree": "f75e962db25ccd3efa81e1fc69ce3e60d228c7a6",
  "parents": [
    "e7e2ee89a9dbf48d70a922d5625cd7320a27cbff"
  ],
  "author": {
    "name": "Vaibhav Nagarnaik",
    "email": "vnagarnaik@google.com",
    "time": "Tue May 03 17:56:42 2011 -0700"
  },
  "committer": {
    "name": "Steven Rostedt",
    "email": "rostedt@goodmis.org",
    "time": "Tue Jun 14 22:04:39 2011 -0400"
  },
  "message": "tracing: Use NUMA allocation for per-cpu ring buffer pages\n\nThe tracing ring buffer is a group of per-cpu ring buffers where\nallocation and logging is done on a per-cpu basis. The events that are\ngenerated on a particular CPU are logged in the corresponding buffer.\nThis is to provide wait-free writes between CPUs and good NUMA node\nlocality while accessing the ring buffer.\n\nHowever, the allocation routines consider NUMA locality only for buffer\npage metadata and not for the actual buffer page. This causes the pages\nto be allocated on the NUMA node local to the CPU where the allocation\nroutine is running at the time.\n\nThis patch fixes the problem by using a NUMA node specific allocation\nroutine so that the pages are allocated from a NUMA node local to the\nlogging CPU.\n\nI tested with the getuid_microbench from autotest. It is a simple binary\nthat calls getuid() in a loop and measures the average time for the\nsyscall to complete. The following command was used to test:\n$ getuid_microbench 1000000\n\nCompared the numbers found on kernel with and without this patch and\nfound that logging latency decreases by 30-50 ns/call.\ntracing with non-NUMA allocation - 569 ns/call\ntracing with NUMA allocation     - 512 ns/call\n\nSigned-off-by: Vaibhav Nagarnaik \u003cvnagarnaik@google.com\u003e\nCc: Frederic Weisbecker \u003cfweisbec@gmail.com\u003e\nCc: Ingo Molnar \u003cmingo@redhat.com\u003e\nCc: Michael Rubin \u003cmrubin@google.com\u003e\nCc: David Sharp \u003cdhsharp@google.com\u003e\nLink: http://lkml.kernel.org/r/1304470602-20366-1-git-send-email-vnagarnaik@google.com\nSigned-off-by: Steven Rostedt \u003crostedt@goodmis.org\u003e\n",
  "tree_diff": [
    {
      "type": "modify",
      "old_id": "ab38ac80b0f9c7c4979a30475626c9bf2fbffa36",
      "old_mode": 33188,
      "old_path": "include/linux/ring_buffer.h",
      "new_id": "b891de96000f35e3eaad5ecd7a6b5128fa6c65ff",
      "new_mode": 33188,
      "new_path": "include/linux/ring_buffer.h"
    },
    {
      "type": "modify",
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      "old_path": "kernel/trace/ring_buffer.c",
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      "new_path": "kernel/trace/ring_buffer.c"
    },
    {
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      "old_mode": 33188,
      "old_path": "kernel/trace/ring_buffer_benchmark.c",
      "new_id": "a5457d577b98313b1ca8b1670ad32a2140001498",
      "new_mode": 33188,
      "new_path": "kernel/trace/ring_buffer_benchmark.c"
    },
    {
      "type": "modify",
      "old_id": "71777c8fe36b3691d3f074dba3da8a4e849cacb0",
      "old_mode": 33188,
      "old_path": "kernel/trace/trace.c",
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}