| Message ID | 1477364358-10620-2-git-send-email-thunder.leizhen@huawei.com |
|---|---|
| State | New |
| Headers | show |
On Tue 25-10-16 10:59:17, Zhen Lei wrote: > If HAVE_MEMORYLESS_NODES is selected, and some memoryless numa nodes are > actually exist. The percpu variable areas and numa control blocks of that > memoryless numa nodes need to be allocated from the nearest available > node to improve performance. > > Although memblock_alloc_try_nid and memblock_virt_alloc_try_nid try the > specified nid at the first time, but if that allocation failed it will > directly drop to use NUMA_NO_NODE. This mean any nodes maybe possible at > the second time. > > To compatible the above old scene, I use a marco node_distance_ready to > control it. By default, the marco node_distance_ready is not defined in > any platforms, the above mentioned functions will work as normal as > before. Otherwise, they will try the nearest node first. I am sorry but it is absolutely unclear to me _what_ is the motivation of the patch. Is this a performance optimization, correctness issue or something else? Could you please restate what is the problem, why do you think it has to be fixed at memblock layer and describe what the actual fix is please? From a quick glance you are trying to bend over the memblock API for something that should be handled on a different layer. > > Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> > --- > mm/memblock.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++--------- > 1 file changed, 65 insertions(+), 11 deletions(-) > > diff --git a/mm/memblock.c b/mm/memblock.c > index 7608bc3..556bbd2 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -1213,9 +1213,71 @@ phys_addr_t __init memblock_alloc(phys_addr_t size, phys_addr_t align) > return memblock_alloc_base(size, align, MEMBLOCK_ALLOC_ACCESSIBLE); > } > > +#ifndef node_distance_ready > +#define node_distance_ready() 0 > +#endif > + > +static phys_addr_t __init memblock_alloc_near_nid(phys_addr_t size, > + phys_addr_t align, phys_addr_t start, > + phys_addr_t end, int nid, ulong flags, > + int alloc_func_type) > +{ > + int nnid, round = 0; > + u64 pa; > + DECLARE_BITMAP(nodes_map, MAX_NUMNODES); > + > + bitmap_zero(nodes_map, MAX_NUMNODES); > + > +again: > + /* > + * There are total 4 cases: > + * <nid == NUMA_NO_NODE> > + * 1)2) node_distance_ready || !node_distance_ready > + * Round 1, nnid = nid = NUMA_NO_NODE; > + * <nid != NUMA_NO_NODE> > + * 3) !node_distance_ready > + * Round 1, nnid = nid; > + * ::Round 2, currently only applicable for alloc_func_type = <0> > + * Round 2, nnid = NUMA_NO_NODE; > + * 4) node_distance_ready > + * Round 1, LOCAL_DISTANCE, nnid = nid; > + * Round ?, nnid = nearest nid; > + */ > + if (!node_distance_ready() || (nid == NUMA_NO_NODE)) { > + nnid = (++round == 1) ? nid : NUMA_NO_NODE; > + } else { > + int i, distance = INT_MAX; > + > + for_each_clear_bit(i, nodes_map, MAX_NUMNODES) > + if (node_distance(nid, i) < distance) { > + nnid = i; > + distance = node_distance(nid, i); > + } > + } > + > + switch (alloc_func_type) { > + case 0: > + pa = memblock_find_in_range_node(size, align, start, end, nnid, flags); > + break; > + > + case 1: > + default: > + pa = memblock_alloc_nid(size, align, nnid); > + if (!node_distance_ready()) > + return pa; > + } > + > + if (!pa && (nnid != NUMA_NO_NODE)) { > + bitmap_set(nodes_map, nnid, 1); > + goto again; > + } > + > + return pa; > +} > + > phys_addr_t __init memblock_alloc_try_nid(phys_addr_t size, phys_addr_t align, int nid) > { > - phys_addr_t res = memblock_alloc_nid(size, align, nid); > + phys_addr_t res = memblock_alloc_near_nid(size, align, 0, 0, nid, 0, 1); > > if (res) > return res; > @@ -1276,19 +1338,11 @@ static void * __init memblock_virt_alloc_internal( > max_addr = memblock.current_limit; > > again: > - alloc = memblock_find_in_range_node(size, align, min_addr, max_addr, > - nid, flags); > + alloc = memblock_alloc_near_nid(size, align, min_addr, max_addr, > + nid, flags, 0); > if (alloc) > goto done; > > - if (nid != NUMA_NO_NODE) { > - alloc = memblock_find_in_range_node(size, align, min_addr, > - max_addr, NUMA_NO_NODE, > - flags); > - if (alloc) > - goto done; > - } > - > if (min_addr) { > min_addr = 0; > goto again; > -- > 2.5.0 > -- Michal Hocko SUSE Labs
On Wed 26-10-16 11:10:44, Leizhen (ThunderTown) wrote: > > > On 2016/10/25 21:23, Michal Hocko wrote: > > On Tue 25-10-16 10:59:17, Zhen Lei wrote: > >> If HAVE_MEMORYLESS_NODES is selected, and some memoryless numa nodes are > >> actually exist. The percpu variable areas and numa control blocks of that > >> memoryless numa nodes need to be allocated from the nearest available > >> node to improve performance. > >> > >> Although memblock_alloc_try_nid and memblock_virt_alloc_try_nid try the > >> specified nid at the first time, but if that allocation failed it will > >> directly drop to use NUMA_NO_NODE. This mean any nodes maybe possible at > >> the second time. > >> > >> To compatible the above old scene, I use a marco node_distance_ready to > >> control it. By default, the marco node_distance_ready is not defined in > >> any platforms, the above mentioned functions will work as normal as > >> before. Otherwise, they will try the nearest node first. > > > > I am sorry but it is absolutely unclear to me _what_ is the motivation > > of the patch. Is this a performance optimization, correctness issue or > > something else? Could you please restate what is the problem, why do you > > think it has to be fixed at memblock layer and describe what the actual > > fix is please? > > This is a performance optimization. Do you have any numbers to back the improvements? > The problem is if some memoryless numa nodes are > actually exist, for example: there are total 4 nodes, 0,1,2,3, node 1 has no memory, > and the node distances is as below: > ---------board------- > | | > | | > socket0 socket1 > / \ / \ > / \ / \ > node0 node1 node2 node3 > distance[1][0] is nearer than distance[1][2] and distance[1][3]. CPUs on node1 access > the memory of node0 is faster than node2 or node3. > > Linux defines a lot of percpu variables, each cpu has a copy of it and most of the time > only to access their own percpu area. In this example, we hope the percpu area of CPUs > on node1 allocated from node0. But without these patches, it's not sure that. I am not familiar with the percpu allocator much so I might be completely missig a point but why cannot this be solved in the percpu allocator directly e.g. by using cpu_to_mem which should already be memoryless aware. Generating a new API while we have means to use an existing one sounds just not right to me. -- Michal Hocko SUSE Labs
On 2016/10/26 17:31, Michal Hocko wrote: > On Wed 26-10-16 11:10:44, Leizhen (ThunderTown) wrote: >> >> >> On 2016/10/25 21:23, Michal Hocko wrote: >>> On Tue 25-10-16 10:59:17, Zhen Lei wrote: >>>> If HAVE_MEMORYLESS_NODES is selected, and some memoryless numa nodes are >>>> actually exist. The percpu variable areas and numa control blocks of that >>>> memoryless numa nodes need to be allocated from the nearest available >>>> node to improve performance. >>>> >>>> Although memblock_alloc_try_nid and memblock_virt_alloc_try_nid try the >>>> specified nid at the first time, but if that allocation failed it will >>>> directly drop to use NUMA_NO_NODE. This mean any nodes maybe possible at >>>> the second time. >>>> >>>> To compatible the above old scene, I use a marco node_distance_ready to >>>> control it. By default, the marco node_distance_ready is not defined in >>>> any platforms, the above mentioned functions will work as normal as >>>> before. Otherwise, they will try the nearest node first. >>> >>> I am sorry but it is absolutely unclear to me _what_ is the motivation >>> of the patch. Is this a performance optimization, correctness issue or >>> something else? Could you please restate what is the problem, why do you >>> think it has to be fixed at memblock layer and describe what the actual >>> fix is please? >> >> This is a performance optimization. > > Do you have any numbers to back the improvements? I have not collected any performance data, but at least in theory, it's beneficial and harmless, except make code looks a bit urly. Because all related functions are actually defined as __init, for example: phys_addr_t __init memblock_alloc_try_nid( void * __init memblock_virt_alloc_try_nid( And all related memory(percpu variables and NODE_DATA) is mostly referred at running time. > >> The problem is if some memoryless numa nodes are >> actually exist, for example: there are total 4 nodes, 0,1,2,3, node 1 has no memory, >> and the node distances is as below: >> ---------board------- >> | | >> | | >> socket0 socket1 >> / \ / \ >> / \ / \ >> node0 node1 node2 node3 >> distance[1][0] is nearer than distance[1][2] and distance[1][3]. CPUs on node1 access >> the memory of node0 is faster than node2 or node3. >> >> Linux defines a lot of percpu variables, each cpu has a copy of it and most of the time >> only to access their own percpu area. In this example, we hope the percpu area of CPUs >> on node1 allocated from node0. But without these patches, it's not sure that. > > I am not familiar with the percpu allocator much so I might be > completely missig a point but why cannot this be solved in the percpu > allocator directly e.g. by using cpu_to_mem which should already be > memoryless aware. My test result told me that it can not: [ 0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x00000011ffffffff] [ 0.000000] Could not find start_pfn for node 1 [ 0.000000] Initmem setup node 1 [mem 0x0000000000000000-0x0000000000000000] [ 0.000000] Initmem setup node 2 [mem 0x0000001200000000-0x00000013ffffffff] [ 0.000000] Initmem setup node 3 [mem 0x0000001400000000-0x00000017ffffffff] [ 14.801895] NODE_DATA(0) = 0x11ffffe500 [ 14.805749] NODE_DATA(1) = 0x11ffffca00 //(1), see below [ 14.809602] NODE_DATA(2) = 0x13ffffe500 [ 14.813455] NODE_DATA(3) = 0x17fffe5480 [ 14.817316] cpu 0 on node0: 11fff87638 [ 14.821083] cpu 1 on node0: 11fff9c638 [ 14.824850] cpu 2 on node0: 11fffb1638 [ 14.828616] cpu 3 on node0: 11fffc6638 [ 14.832383] cpu 4 on node1: 17fff8a638 //(2), see below [ 14.836149] cpu 5 on node1: 17fff9f638 [ 14.839912] cpu 6 on node1: 17fffb4638 [ 14.843677] cpu 7 on node1: 17fffc9638 [ 14.847444] cpu 8 on node2: 13fffa4638 [ 14.851210] cpu 9 on node2: 13fffb9638 [ 14.854976] cpu10 on node2: 13fffce638 [ 14.858742] cpu11 on node2: 13fffe3638 [ 14.862510] cpu12 on node3: 17fff36638 [ 14.866276] cpu13 on node3: 17fff4b638 [ 14.870042] cpu14 on node3: 17fff60638 [ 14.873809] cpu15 on node3: 17fff75638 (1) memblock_alloc_try_nid and with these patches, memory was allocated from node0 (2) do the same implementation as X86 and PowerPC, memory was allocated from node3: return __alloc_bootmem_node(NODE_DATA(nid), size, align, __pa(MAX_DMA_ADDRESS)); I'm not sure how about on X86 and PowerPC, here is my test cases. Is anybody interested and have testing environment, can you help me to execute it? static int tst_numa_002(void) { int i; for (i = 0; i < nr_node_ids; i++) pr_info("NODE_DATA(%d) = 0x%llx\n", i, virt_to_phys(NODE_DATA(i))); return 0; } static int tst_numa_003(void) { int cpu; void __percpu *p; p = __alloc_percpu(0x100, 1); for_each_possible_cpu(cpu) pr_info("cpu%2d on node%d: %llx\n", cpu, cpu_to_node(cpu), per_cpu_ptr_to_phys(per_cpu_ptr(p, cpu))); free_percpu(p); return 0; } > > Generating a new API while we have means to use an existing one sounds > just not right to me. Yes, so I gave up to create two new functions and selected this implementation. >
On Thu 27-10-16 10:41:24, Leizhen (ThunderTown) wrote: > > > On 2016/10/26 17:31, Michal Hocko wrote: > > On Wed 26-10-16 11:10:44, Leizhen (ThunderTown) wrote: > >> > >> > >> On 2016/10/25 21:23, Michal Hocko wrote: > >>> On Tue 25-10-16 10:59:17, Zhen Lei wrote: > >>>> If HAVE_MEMORYLESS_NODES is selected, and some memoryless numa nodes are > >>>> actually exist. The percpu variable areas and numa control blocks of that > >>>> memoryless numa nodes need to be allocated from the nearest available > >>>> node to improve performance. > >>>> > >>>> Although memblock_alloc_try_nid and memblock_virt_alloc_try_nid try the > >>>> specified nid at the first time, but if that allocation failed it will > >>>> directly drop to use NUMA_NO_NODE. This mean any nodes maybe possible at > >>>> the second time. > >>>> > >>>> To compatible the above old scene, I use a marco node_distance_ready to > >>>> control it. By default, the marco node_distance_ready is not defined in > >>>> any platforms, the above mentioned functions will work as normal as > >>>> before. Otherwise, they will try the nearest node first. > >>> > >>> I am sorry but it is absolutely unclear to me _what_ is the motivation > >>> of the patch. Is this a performance optimization, correctness issue or > >>> something else? Could you please restate what is the problem, why do you > >>> think it has to be fixed at memblock layer and describe what the actual > >>> fix is please? > >> > >> This is a performance optimization. > > > > Do you have any numbers to back the improvements? > > I have not collected any performance data, but at least in theory, > it's beneficial and harmless, except make code looks a bit > urly. The whole memoryless area is cluttered with hacks because everybody just adds pieces here and there to make his particular usecase work IMHO. Adding more on top for performance reasons which are even not measured to prove a clear win is a no go. Please step back try to think how this could be done with an existing infrastructure we have (some cleanups while doing that would be hugely appreciated) and if that is not possible then explain why and why it is not feasible to fix that before you start adding a new API. Thanks! -- Michal Hocko SUSE Labs
diff --git a/mm/memblock.c b/mm/memblock.c index 7608bc3..556bbd2 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -1213,9 +1213,71 @@ phys_addr_t __init memblock_alloc(phys_addr_t size, phys_addr_t align) return memblock_alloc_base(size, align, MEMBLOCK_ALLOC_ACCESSIBLE); } +#ifndef node_distance_ready +#define node_distance_ready() 0 +#endif + +static phys_addr_t __init memblock_alloc_near_nid(phys_addr_t size, + phys_addr_t align, phys_addr_t start, + phys_addr_t end, int nid, ulong flags, + int alloc_func_type) +{ + int nnid, round = 0; + u64 pa; + DECLARE_BITMAP(nodes_map, MAX_NUMNODES); + + bitmap_zero(nodes_map, MAX_NUMNODES); + +again: + /* + * There are total 4 cases: + * <nid == NUMA_NO_NODE> + * 1)2) node_distance_ready || !node_distance_ready + * Round 1, nnid = nid = NUMA_NO_NODE; + * <nid != NUMA_NO_NODE> + * 3) !node_distance_ready + * Round 1, nnid = nid; + * ::Round 2, currently only applicable for alloc_func_type = <0> + * Round 2, nnid = NUMA_NO_NODE; + * 4) node_distance_ready + * Round 1, LOCAL_DISTANCE, nnid = nid; + * Round ?, nnid = nearest nid; + */ + if (!node_distance_ready() || (nid == NUMA_NO_NODE)) { + nnid = (++round == 1) ? nid : NUMA_NO_NODE; + } else { + int i, distance = INT_MAX; + + for_each_clear_bit(i, nodes_map, MAX_NUMNODES) + if (node_distance(nid, i) < distance) { + nnid = i; + distance = node_distance(nid, i); + } + } + + switch (alloc_func_type) { + case 0: + pa = memblock_find_in_range_node(size, align, start, end, nnid, flags); + break; + + case 1: + default: + pa = memblock_alloc_nid(size, align, nnid); + if (!node_distance_ready()) + return pa; + } + + if (!pa && (nnid != NUMA_NO_NODE)) { + bitmap_set(nodes_map, nnid, 1); + goto again; + } + + return pa; +} + phys_addr_t __init memblock_alloc_try_nid(phys_addr_t size, phys_addr_t align, int nid) { - phys_addr_t res = memblock_alloc_nid(size, align, nid); + phys_addr_t res = memblock_alloc_near_nid(size, align, 0, 0, nid, 0, 1); if (res) return res; @@ -1276,19 +1338,11 @@ static void * __init memblock_virt_alloc_internal( max_addr = memblock.current_limit; again: - alloc = memblock_find_in_range_node(size, align, min_addr, max_addr, - nid, flags); + alloc = memblock_alloc_near_nid(size, align, min_addr, max_addr, + nid, flags, 0); if (alloc) goto done; - if (nid != NUMA_NO_NODE) { - alloc = memblock_find_in_range_node(size, align, min_addr, - max_addr, NUMA_NO_NODE, - flags); - if (alloc) - goto done; - } - if (min_addr) { min_addr = 0; goto again;
If HAVE_MEMORYLESS_NODES is selected, and some memoryless numa nodes are actually exist. The percpu variable areas and numa control blocks of that memoryless numa nodes need to be allocated from the nearest available node to improve performance. Although memblock_alloc_try_nid and memblock_virt_alloc_try_nid try the specified nid at the first time, but if that allocation failed it will directly drop to use NUMA_NO_NODE. This mean any nodes maybe possible at the second time. To compatible the above old scene, I use a marco node_distance_ready to control it. By default, the marco node_distance_ready is not defined in any platforms, the above mentioned functions will work as normal as before. Otherwise, they will try the nearest node first. Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> --- mm/memblock.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 65 insertions(+), 11 deletions(-) -- 2.5.0