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From: kernel test robot <rong.a.chen@intel.com>
To: Ming Lei <ming.lei@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Jens Axboe <axboe@kernel.dk>
Cc: clang-built-linux@googlegroups.com, kbuild-all@lists.01.org,
	linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
	Christoph Hellwig <hch@lst.de>, Ming Lei <ming.lei@redhat.com>
Subject: Re: [PATCH 5/7] genirq/affinity: move group_cpus_evenly() into lib/
Date: Mon, 16 Aug 2021 18:08:15 +0800	[thread overview]
Message-ID: <05fd64eb-495a-be42-7ec9-f48b9a3eeab6@intel.com> (raw)
In-Reply-To: <202108150937.Qdn6klQB-lkp@intel.com>

[-- Attachment #1: Type: text/plain, Size: 23074 bytes --]


Hi Ming,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tip/irq/core]
[also build test WARNING on next-20210813]
[cannot apply to block/for-next linux/master linus/master v5.14-rc5]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url: 
https://github.com/0day-ci/linux/commits/Ming-Lei/genirq-affinity-abstract-new-API-from-managed-irq-affinity-spread/20210814-203741
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 
04c2721d3530f0723b4c922a8fa9f26b202a20de
config: x86_64-randconfig-c001-20210814 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 
1f7b25ea76a925aca690da28de9d78db7ca99d0c)
reproduce (this is a W=1 build):
         wget 
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross 
-O ~/bin/make.cross
         chmod +x ~/bin/make.cross
         # install x86_64 cross compiling tool for clang build
         # apt-get install binutils-x86-64-linux-gnu
         # 
https://github.com/0day-ci/linux/commit/759f72186bfdd5c3ba8b53ac0749cf7ba930012c
         git remote add linux-review https://github.com/0day-ci/linux
         git fetch --no-tags linux-review 
Ming-Lei/genirq-affinity-abstract-new-API-from-managed-irq-affinity-spread/20210814-203741
         git checkout 759f72186bfdd5c3ba8b53ac0749cf7ba930012c
         # save the attached .config to linux build tree
         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross 
ARCH=x86_64 clang-analyzer
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>


clang-analyzer warnings: (new ones prefixed by >>)
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    7 warnings generated.
    Suppressed 7 warnings (6 in non-user code, 1 with check filters).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    5 warnings generated.
    Suppressed 5 warnings (5 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    5 warnings generated.
    Suppressed 5 warnings (5 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    5 warnings generated.
    Suppressed 5 warnings (5 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    5 warnings generated.
    Suppressed 5 warnings (5 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    3 warnings generated.
    Suppressed 3 warnings (3 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    7 warnings generated.
    lib/glob.c:48:32: warning: Assigned value is garbage or undefined 
[clang-analyzer-core.uninitialized.Assign]
            char const *back_pat = NULL, *back_str = back_str;
                                          ^          ~~~~~~~~
    lib/glob.c:48:32: note: Assigned value is garbage or undefined
            char const *back_pat = NULL, *back_str = back_str;
                                          ^          ~~~~~~~~
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    7 warnings generated.
    lib/strnlen_user.c:34:2: warning: Value stored to 'src' is never 
read [clang-analyzer-deadcode.DeadStores]
            src -= align;
            ^      ~~~~~
    lib/strnlen_user.c:34:2: note: Value stored to 'src' is never read
            src -= align;
            ^      ~~~~~
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    7 warnings generated.
    Suppressed 7 warnings (7 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    7 warnings generated.
    Suppressed 7 warnings (7 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    6 warnings generated.
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    7 warnings generated.
    lib/oid_registry.c:149:3: warning: Value stored to 'num' is never 
read [clang-analyzer-deadcode.DeadStores]
                    num = 0;
                    ^     ~
    lib/oid_registry.c:149:3: note: Value stored to 'num' is never read
                    num = 0;
                    ^     ~
    Suppressed 6 warnings (6 in non-user code).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    9 warnings generated.
    Suppressed 9 warnings (2 in non-user code, 7 with check filters).
    Use -header-filter=.* to display errors from all non-system headers. 
Use -system-headers to display errors from system headers as well.
    7 warnings generated.
>> lib/group_cpus.c:236:22: warning: Division by zero [clang-analyzer-core.DivideZero]
                                     numgrps * ncpus / remaining_ncpus);
                                                     ^
    lib/group_cpus.c:352:2: note: Taking false branch
            if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
            ^
    lib/group_cpus.c:355:2: note: Taking false branch
            if (!zalloc_cpumask_var(&npresmsk, GFP_KERNEL))
            ^
    lib/group_cpus.c:359:7: note: 'node_to_cpumask' is non-null
            if (!node_to_cpumask)
                 ^~~~~~~~~~~~~~~
    lib/group_cpus.c:359:2: note: Taking false branch
            if (!node_to_cpumask)
            ^
    lib/group_cpus.c:363:6: note: Assuming 'masks' is non-null
            if (!masks)
                ^~~~~~
    lib/group_cpus.c:363:2: note: Taking false branch
            if (!masks)
            ^
    lib/group_cpus.c:371:8: note: Calling '__group_cpus_evenly'
            ret = __group_cpus_evenly(curgrp, numgrps, node_to_cpumask,
                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    lib/group_cpus.c:257:6: note: Assuming the condition is false
            if (!cpumask_weight(cpu_mask))
                ^~~~~~~~~~~~~~~~~~~~~~~~~
    lib/group_cpus.c:257:2: note: Taking false branch
            if (!cpumask_weight(cpu_mask))
            ^
    lib/group_cpus.c:266:6: note: Assuming 'numgrps' is > 'nodes'
            if (numgrps <= nodes) {
                ^~~~~~~~~~~~~~~~
    lib/group_cpus.c:266:2: note: Taking false branch
            if (numgrps <= nodes) {
            ^
    lib/group_cpus.c:279:6: note: Assuming 'node_groups' is non-null
            if (!node_groups)
                ^~~~~~~~~~~~
    lib/group_cpus.c:279:2: note: Taking false branch
            if (!node_groups)
            ^
    lib/group_cpus.c:283:2: note: Calling 'alloc_nodes_groups'
            alloc_nodes_groups(numgrps, node_to_cpumask, cpu_mask,
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    lib/group_cpus.c:134:14: note: 'remaining_ncpus' initialized to 0
            unsigned n, remaining_ncpus = 0;
                        ^~~~~~~~~~~~~~~
    lib/group_cpus.c:136:2: note: Loop condition is true.  Entering loop 
body
            for (n = 0; n < nr_node_ids; n++) {
            ^
    lib/group_cpus.c:136:2: note: Loop condition is false. Execution 
continues on line 141
    lib/group_cpus.c:141:2: note: Taking false branch
            for_each_node_mask(n, nodemsk) {
            ^
    include/linux/nodemask.h:384:2: note: expanded from macro 
'for_each_node_mask'
            if (!nodes_empty(mask))                         \
            ^
    lib/group_cpus.c:153:12: note: '__UNIQUE_ID___x401' is < 
'__UNIQUE_ID___y402'
            numgrps = min_t(unsigned, remaining_ncpus, numgrps);
                      ^
    include/linux/minmax.h:104:27: note: expanded from macro 'min_t'
    #define min_t(type, x, y)       __careful_cmp((type)(x), (type)(y), <)
                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    include/linux/minmax.h:38:3: note: expanded from macro '__careful_cmp'
                    __cmp_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y), 
op))
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    include/linux/minmax.h:33:3: note: expanded from macro '__cmp_once'
                    __cmp(unique_x, unique_y, op); })
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    include/linux/minmax.h:28:26: note: expanded from macro '__cmp'
    #define __cmp(x, y, op) ((x) op (y) ? (x) : (y))
                             ^~~
    lib/group_cpus.c:153:12: note: '?' condition is true
            numgrps = min_t(unsigned, remaining_ncpus, numgrps);
                      ^
    include/linux/minmax.h:104:27: note: expanded from macro 'min_t'
    #define min_t(type, x, y)       __careful_cmp((type)(x), (type)(y), <)
                                    ^
    include/linux/minmax.h:38:3: note: expanded from macro '__careful_cmp'
                    __cmp_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y), 
op))
                    ^
    include/linux/minmax.h:33:3: note: expanded from macro '__cmp_once'
                    __cmp(unique_x, unique_y, op); })
                    ^
    include/linux/minmax.h:28:26: note: expanded from macro '__cmp'
    #define __cmp(x, y, op) ((x) op (y) ? (x) : (y))
                             ^
    lib/group_cpus.c:226:2: note: Loop condition is true.  Entering loop 
body
            for (n = 0; n < nr_node_ids; n++) {
            ^
    lib/group_cpus.c:229:7: note: Assuming the condition is false
                    if (node_groups[n].ncpus == UINT_MAX)
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    lib/group_cpus.c:229:3: note: Taking false branch
                    if (node_groups[n].ncpus == UINT_MAX)
                    ^
    lib/group_cpus.c:232:3: note: Taking true branch
                    WARN_ON_ONCE(numgrps == 0);
                    ^
    include/asm-generic/bug.h:105:2: note: expanded from macro 
'WARN_ON_ONCE'

vim +236 lib/group_cpus.c

759f72186bfdd5 Ming Lei 2021-08-14  113  759f72186bfdd5 Ming Lei 
2021-08-14  114  /*
759f72186bfdd5 Ming Lei 2021-08-14  115   * Allocate group number for 
each node, so that for each node:
759f72186bfdd5 Ming Lei 2021-08-14  116   *
759f72186bfdd5 Ming Lei 2021-08-14  117   * 1) the allocated number is >= 1
759f72186bfdd5 Ming Lei 2021-08-14  118   *
759f72186bfdd5 Ming Lei 2021-08-14  119   * 2) the allocated number is 
<= active CPU number of this node
759f72186bfdd5 Ming Lei 2021-08-14  120   *
759f72186bfdd5 Ming Lei 2021-08-14  121   * The actual allocated total 
groups may be less than @numgrps when
759f72186bfdd5 Ming Lei 2021-08-14  122   * active total CPU number is 
less than @numgrps.
759f72186bfdd5 Ming Lei 2021-08-14  123   *
759f72186bfdd5 Ming Lei 2021-08-14  124   * Active CPUs means the CPUs 
in '@cpu_mask AND @node_to_cpumask[]'
759f72186bfdd5 Ming Lei 2021-08-14  125   * for each node.
759f72186bfdd5 Ming Lei 2021-08-14  126   */
759f72186bfdd5 Ming Lei 2021-08-14  127  static void 
alloc_nodes_groups(unsigned int numgrps,
759f72186bfdd5 Ming Lei 2021-08-14  128  			       cpumask_var_t 
*node_to_cpumask,
759f72186bfdd5 Ming Lei 2021-08-14  129  			       const struct cpumask 
*cpu_mask,
759f72186bfdd5 Ming Lei 2021-08-14  130  			       const nodemask_t nodemsk,
759f72186bfdd5 Ming Lei 2021-08-14  131  			       struct cpumask *nmsk,
759f72186bfdd5 Ming Lei 2021-08-14  132  			       struct node_groups 
*node_groups)
759f72186bfdd5 Ming Lei 2021-08-14  133  {
759f72186bfdd5 Ming Lei 2021-08-14  134  	unsigned n, remaining_ncpus = 0;
759f72186bfdd5 Ming Lei 2021-08-14  135  759f72186bfdd5 Ming Lei 
2021-08-14  136  	for (n = 0; n < nr_node_ids; n++) {
759f72186bfdd5 Ming Lei 2021-08-14  137  		node_groups[n].id = n;
759f72186bfdd5 Ming Lei 2021-08-14  138  		node_groups[n].ncpus = UINT_MAX;
759f72186bfdd5 Ming Lei 2021-08-14  139  	}
759f72186bfdd5 Ming Lei 2021-08-14  140  759f72186bfdd5 Ming Lei 
2021-08-14  141  	for_each_node_mask(n, nodemsk) {
759f72186bfdd5 Ming Lei 2021-08-14  142  		unsigned ncpus;
759f72186bfdd5 Ming Lei 2021-08-14  143  759f72186bfdd5 Ming Lei 
2021-08-14  144  		cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
759f72186bfdd5 Ming Lei 2021-08-14  145  		ncpus = cpumask_weight(nmsk);
759f72186bfdd5 Ming Lei 2021-08-14  146  759f72186bfdd5 Ming Lei 
2021-08-14  147  		if (!ncpus)
759f72186bfdd5 Ming Lei 2021-08-14  148  			continue;
759f72186bfdd5 Ming Lei 2021-08-14  149  		remaining_ncpus += ncpus;
759f72186bfdd5 Ming Lei 2021-08-14  150  		node_groups[n].ncpus = ncpus;
759f72186bfdd5 Ming Lei 2021-08-14  151  	}
759f72186bfdd5 Ming Lei 2021-08-14  152  759f72186bfdd5 Ming Lei 
2021-08-14  153  	numgrps = min_t(unsigned, remaining_ncpus, numgrps);
759f72186bfdd5 Ming Lei 2021-08-14  154  759f72186bfdd5 Ming Lei 
2021-08-14  155  	sort(node_groups, nr_node_ids, sizeof(node_groups[0]),
759f72186bfdd5 Ming Lei 2021-08-14  156  	     ncpus_cmp_func, NULL);
759f72186bfdd5 Ming Lei 2021-08-14  157  759f72186bfdd5 Ming Lei 
2021-08-14  158  	/*
759f72186bfdd5 Ming Lei 2021-08-14  159  	 * Allocate groups for each 
node according to the ratio of this
759f72186bfdd5 Ming Lei 2021-08-14  160  	 * node's nr_cpus to remaining 
un-assigned ncpus. 'numgrps' is
759f72186bfdd5 Ming Lei 2021-08-14  161  	 * bigger than number of 
active numa nodes. Always start the
759f72186bfdd5 Ming Lei 2021-08-14  162  	 * allocation from the node 
with minimized nr_cpus.
759f72186bfdd5 Ming Lei 2021-08-14  163  	 *
759f72186bfdd5 Ming Lei 2021-08-14  164  	 * This way guarantees that 
each active node gets allocated at
759f72186bfdd5 Ming Lei 2021-08-14  165  	 * least one group, and the 
theory is simple: over-allocation
759f72186bfdd5 Ming Lei 2021-08-14  166  	 * is only done when this node 
is assigned by one group, so
759f72186bfdd5 Ming Lei 2021-08-14  167  	 * other nodes will be 
allocated >= 1 groups, since 'numgrps' is
759f72186bfdd5 Ming Lei 2021-08-14  168  	 * bigger than number of numa 
nodes.
759f72186bfdd5 Ming Lei 2021-08-14  169  	 *
759f72186bfdd5 Ming Lei 2021-08-14  170  	 * One perfect invariant is 
that number of allocated groups for
759f72186bfdd5 Ming Lei 2021-08-14  171  	 * each node is <= CPU count 
of this node:
759f72186bfdd5 Ming Lei 2021-08-14  172  	 *
759f72186bfdd5 Ming Lei 2021-08-14  173  	 * 1) suppose there are two 
nodes: A and B
759f72186bfdd5 Ming Lei 2021-08-14  174  	 * 	ncpu(X) is CPU count of node X
759f72186bfdd5 Ming Lei 2021-08-14  175  	 * 	grps(X) is the group count 
allocated to node X via this
759f72186bfdd5 Ming Lei 2021-08-14  176  	 * 	algorithm
759f72186bfdd5 Ming Lei 2021-08-14  177  	 *
759f72186bfdd5 Ming Lei 2021-08-14  178  	 * 	ncpu(A) <= ncpu(B)
759f72186bfdd5 Ming Lei 2021-08-14  179  	 * 	ncpu(A) + ncpu(B) = N
759f72186bfdd5 Ming Lei 2021-08-14  180  	 * 	grps(A) + grps(B) = G
759f72186bfdd5 Ming Lei 2021-08-14  181  	 *
759f72186bfdd5 Ming Lei 2021-08-14  182  	 * 	grps(A) = max(1, 
round_down(G * ncpu(A) / N))
759f72186bfdd5 Ming Lei 2021-08-14  183  	 * 	grps(B) = G - grps(A)
759f72186bfdd5 Ming Lei 2021-08-14  184  	 *
759f72186bfdd5 Ming Lei 2021-08-14  185  	 * 	both N and G are integer, 
and 2 <= G <= N, suppose
759f72186bfdd5 Ming Lei 2021-08-14  186  	 * 	G = N - delta, and 0 <= 
delta <= N - 2
759f72186bfdd5 Ming Lei 2021-08-14  187  	 *
759f72186bfdd5 Ming Lei 2021-08-14  188  	 * 2) obviously grps(A) <= 
ncpu(A) because:
759f72186bfdd5 Ming Lei 2021-08-14  189  	 *
759f72186bfdd5 Ming Lei 2021-08-14  190  	 * 	if grps(A) is 1, then 
grps(A) <= ncpu(A) given
759f72186bfdd5 Ming Lei 2021-08-14  191  	 * 	ncpu(A) >= 1
759f72186bfdd5 Ming Lei 2021-08-14  192  	 *
759f72186bfdd5 Ming Lei 2021-08-14  193  	 * 	otherwise,
759f72186bfdd5 Ming Lei 2021-08-14  194  	 * 		grps(A) <= G * ncpu(A) / 
N <= ncpu(A), given G <= N
759f72186bfdd5 Ming Lei 2021-08-14  195  	 *
759f72186bfdd5 Ming Lei 2021-08-14  196  	 * 3) prove how grps(B) <= 
ncpu(B):
759f72186bfdd5 Ming Lei 2021-08-14  197  	 *
759f72186bfdd5 Ming Lei 2021-08-14  198  	 * 	if round_down(G * ncpu(A) 
/ N) == 0, vecs(B) won't be
759f72186bfdd5 Ming Lei 2021-08-14  199  	 * 	over-allocated, so grps(B) 
<= ncpu(B),
759f72186bfdd5 Ming Lei 2021-08-14  200  	 *
759f72186bfdd5 Ming Lei 2021-08-14  201  	 * 	otherwise:
759f72186bfdd5 Ming Lei 2021-08-14  202  	 *
759f72186bfdd5 Ming Lei 2021-08-14  203  	 * 	grps(A) =
759f72186bfdd5 Ming Lei 2021-08-14  204  	 * 		round_down(G * ncpu(A) / N) =
759f72186bfdd5 Ming Lei 2021-08-14  205  	 * 		round_down((N - delta) * 
ncpu(A) / N) =
759f72186bfdd5 Ming Lei 2021-08-14  206  	 * 		round_down((N * ncpu(A) - 
delta * ncpu(A)) / N)	 >=
759f72186bfdd5 Ming Lei 2021-08-14  207  	 * 		round_down((N * ncpu(A) - 
delta * N) / N)	 =
759f72186bfdd5 Ming Lei 2021-08-14  208  	 * 		cpu(A) - delta
759f72186bfdd5 Ming Lei 2021-08-14  209  	 *
759f72186bfdd5 Ming Lei 2021-08-14  210  	 * 	then:
759f72186bfdd5 Ming Lei 2021-08-14  211  	 *
759f72186bfdd5 Ming Lei 2021-08-14  212  	 * 	grps(A) - G >= ncpu(A) - 
delta - G
759f72186bfdd5 Ming Lei 2021-08-14  213  	 * 	=>
759f72186bfdd5 Ming Lei 2021-08-14  214  	 * 	G - grps(A) <= G + delta - 
ncpu(A)
759f72186bfdd5 Ming Lei 2021-08-14  215  	 * 	=>
759f72186bfdd5 Ming Lei 2021-08-14  216  	 * 	grps(B) <= N - ncpu(A)
759f72186bfdd5 Ming Lei 2021-08-14  217  	 * 	=>
759f72186bfdd5 Ming Lei 2021-08-14  218  	 * 	grps(B) <= cpu(B)
759f72186bfdd5 Ming Lei 2021-08-14  219  	 *
759f72186bfdd5 Ming Lei 2021-08-14  220  	 * For nodes >= 3, it can be 
thought as one node and another big
759f72186bfdd5 Ming Lei 2021-08-14  221  	 * node given that is exactly 
what this algorithm is implemented,
759f72186bfdd5 Ming Lei 2021-08-14  222  	 * and we always re-calculate 
'remaining_ncpus' & 'numgrps', and
759f72186bfdd5 Ming Lei 2021-08-14  223  	 * finally for each node X: 
grps(X) <= ncpu(X).
759f72186bfdd5 Ming Lei 2021-08-14  224  	 *
759f72186bfdd5 Ming Lei 2021-08-14  225  	 */
759f72186bfdd5 Ming Lei 2021-08-14  226  	for (n = 0; n < nr_node_ids; 
n++) {
759f72186bfdd5 Ming Lei 2021-08-14  227  		unsigned ngroups, ncpus;
759f72186bfdd5 Ming Lei 2021-08-14  228  759f72186bfdd5 Ming Lei 
2021-08-14  229  		if (node_groups[n].ncpus == UINT_MAX)
759f72186bfdd5 Ming Lei 2021-08-14  230  			continue;
759f72186bfdd5 Ming Lei 2021-08-14  231  759f72186bfdd5 Ming Lei 
2021-08-14  232  		WARN_ON_ONCE(numgrps == 0);
759f72186bfdd5 Ming Lei 2021-08-14  233  759f72186bfdd5 Ming Lei 
2021-08-14  234  		ncpus = node_groups[n].ncpus;
759f72186bfdd5 Ming Lei 2021-08-14  235  		ngroups = max_t(unsigned, 1,
759f72186bfdd5 Ming Lei 2021-08-14 @236  				 numgrps * ncpus / 
remaining_ncpus);
759f72186bfdd5 Ming Lei 2021-08-14  237  		WARN_ON_ONCE(ngroups > ncpus);
759f72186bfdd5 Ming Lei 2021-08-14  238  759f72186bfdd5 Ming Lei 
2021-08-14  239  		node_groups[n].ngroups = ngroups;
759f72186bfdd5 Ming Lei 2021-08-14  240  759f72186bfdd5 Ming Lei 
2021-08-14  241  		remaining_ncpus -= ncpus;
759f72186bfdd5 Ming Lei 2021-08-14  242  		numgrps -= ngroups;
759f72186bfdd5 Ming Lei 2021-08-14  243  	}
759f72186bfdd5 Ming Lei 2021-08-14  244  }
759f72186bfdd5 Ming Lei 2021-08-14  245
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org


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       reply	other threads:[~2021-08-16 10:08 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <202108150937.Qdn6klQB-lkp@intel.com>
2021-08-16 10:08 ` kernel test robot [this message]
2021-08-14 12:35 [PATCH 0/7] genirq/affinity: abstract new API from managed irq affinity spread Ming Lei
2021-08-14 12:35 ` [PATCH 5/7] genirq/affinity: move group_cpus_evenly() into lib/ Ming Lei
2021-08-14 17:01   ` kernel test robot
2021-08-16  1:04     ` Ming Lei
2021-08-17  4:52       ` Christoph Hellwig
2021-08-14 17:15   ` kernel test robot

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