Messages in this thread | | | Date | Mon, 30 Nov 2015 01:21:55 +0900 | From | Namhyung Kim <> | Subject | Re: RFC Re: [PATCH v2 04/13] perf tools: Add API to config maps in bpf object |
| |
Hi Arnaldo,
On Fri, Nov 27, 2015 at 10:10:54PM -0300, Arnaldo Carvalho de Melo wrote: > Em Fri, Nov 27, 2015 at 08:47:38AM +0000, Wang Nan escreveu: > > bpf__config_obj() is introduced as a core API to config BPF object > > after loading. One configuration option of maps is introduced. After > > this patch BPF object can accept configuration like: > > > > maps:my_map:value=1234 > > > > (maps.my_map.value looks pretty. However, there's a small but hard > > to fixed problem related to flex's greedy matching. Please see [1]. > > Choose ':' to avoid it in a simpler way.) > > Understood the issues, but I would like to hear from Ingo, Jiri, > Namhyung, Brian and others here, since we're setting up syntax, and yes, > using: > > maps.my_map.value[0,3...6]=1234; > > or even: > > maps->my_map->value[0,3...6]=1234; > > Looks more natural than: > > maps:my_map:value[0,3...6]=1234;
Do we have to use only single separator? What about this?
maps:my_map.value[0,3...6]=1234;
Thanks, Namhyung
> > I'll think harder about this, maybe we can find a way to use the more > familiar dot notation somehow. > > And I have to anyway test this more extensively, so I'll push the > patches I have and try this as soon as I can. > > - Arnaldo > > > > This patch is more complex than the work it really does because the > > consideration of extension. In designing of BPF map configuration, > > following things should be considered: > > > > 1. Array indics selection: perf should allow user setting different > > indices :-) > > > value to different slots in an array, with syntax like: > > maps:my_map:value[0,3...6]=1234; > > > > 2. A map can be config by different config terms, each for a part > > of it. For example, set each slot to pid of a thread; > > > > 3. Type of value: integer is not the only valid value type. Perf > > event can also be put into a map after commit 35578d7984003097af2b1e3 > > (bpf: Implement function bpf_perf_event_read() that get the selected > > hardware PMU conuter); > > > > 4. For hash table, it is possible to use string or other as key; > > > > 5. It is possible that map configuration is unable to be setup > > during parsing. Perf event is an example. > > > > Therefore, this patch does following: > > > > 1. Instead of updating map element during parsing, this patch stores > > map config options in 'struct bpf_map_priv'. Following patches > > would apply those configs at proper time; > > > > 2. Link map operations to a list so a map can have multiple config > > terms attached, so different parts can be configured separately; > > > > 3. Make 'struct bpf_map_priv' extensible so following patches can > > add new types of keys and operations; > > > > 4. Use bpf_config_map_funcs array to support more maps config options. > > > > Since the patch changing event parser to parse BPF object config is > > relative large, I put in another commit. Code in this patch > > could be tested after applying next patch. > > > > [1] http://lkml.kernel.org/g/564ED621.4050500@huawei.com > > > Signed-off-by: Wang Nan <wangnan0@huawei.com> > > Signed-off-by: He Kuang <hekuang@huawei.com> > > Cc: Alexei Starovoitov <ast@kernel.org> > > Cc: Arnaldo Carvalho de Melo <acme@redhat.com> > > Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> > > Cc: Namhyung Kim <namhyung@kernel.org> > > Cc: Zefan Li <lizefan@huawei.com> > > Cc: pi3orama@163.com
| |