Messages in this thread | | | Date | Mon, 23 Oct 2017 16:04:53 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v7 0/5] generate full callchain cursor entries for inlined frames |
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Em Fri, Oct 20, 2017 at 10:21:03PM +0200, Milian Wolff escreveu: > On Freitag, 20. Oktober 2017 18:15:40 CEST Arnaldo Carvalho de Melo wrote: > > Em Thu, Oct 19, 2017 at 01:38:31PM +0200, Milian Wolff escreveu: > > > This series of patches completely reworks the way inline frames are > > > handled. Instead of querying for the inline nodes on-demand in the > > > individual tools, we now create proper callchain nodes for inlined > > > frames. The advantages this approach brings are numerous: > > > > > > - less duplicated code in the individual browser > > > - aggregated cost for inlined frames for the --children top-down list > > > - various bug fixes that arose from querying for a srcline/symbol based on > > > > > > the IP of a sample, which will always point to the last inlined frame > > > instead of the corresponding non-inlined frame > > > > > > - overall much better support for visualizing cost for heavily-inlined C++ > > > > > > code, which simply was confusing and unreliably before > > > > > > - srcline honors the global setting as to whether full paths or basenames > > > > > > should be shown > > > > > > - caches for inlined frames and srcline information, which allow us to > > > > > > enable inline frame handling by default > > > > > > For comparison, below lists the output before and after for `perf script` > > > > > and `perf report`. The example file I used to generate the perf data is: > > > > So, please check my tmp.perf/core branch, it has this patchset + the fix > > I proposed for the match_chain() to always use absolute addresses. > > OK, so I've looked at it. I think there are some style issues with the > indentation in match_chain_addresses. Also, the unmap_ip lines are too long > for checkpatch.pl > > Additionally, we can now still run into the CCKEY_ADDRESS code path (when > match_chain_strings for inlined symbols returns MATCH_ERROR, or when either > cnode->ms.sym or node->sym is invalid), but won't unmap the IP properly then.
so you're saying that cnode->ip and node->ip may be relative or absolute? I thought they were always absolute, but I'll double check.
> Can we maybe instead use something like this on top of your patch? > > diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c > index 01fc95fdd1e0..92bca95be202 100644 > --- a/tools/perf/util/callchain.c > +++ b/tools/perf/util/callchain.c > @@ -669,11 +669,16 @@ static enum match_result match_chain_strings(const char > *left, > static enum match_result match_chain_addresses(u64 left_ip, u64 right_ip) > { > if (left_ip == right_ip) > - return MATCH_EQ; > - else if (left_ip < right_ip) > - return MATCH_LT; > - else > - return MATCH_GT; > + return MATCH_EQ; > + else if (left_ip < right_ip) > + return MATCH_LT; > + else > + return MATCH_GT; > +}
Applied the space fixes above, but the following I don't think makes things clearer, it is not "unmap_ip()" it is at its best try_to_unmap_ip_but_do_not_unmap_if_not_possible() which is confusing 8-)
So we better fix it in the users and continue using the existing map->unmap_ip(map, rel_ip) idiom.
> +static u64 unmap_ip(struct map *map, u64 ip) > +{ > + return map ? map->unmap_ip(map, ip) : ip; > } > > static enum match_result match_chain(struct callchain_cursor_node *node, > @@ -702,9 +707,10 @@ static enum match_result match_chain(struct > callchain_cursor_node *node, > if (match != MATCH_ERROR) > break; > } else { > - u64 left = cnode->ms.map->unmap_ip(cnode->ms.map, cnode- > >ms.sym->start), > - right = node->map->unmap_ip(node->map, node->sym->start); > - > + u64 left = unmap_ip(cnode->ms.map, > + cnode->ms.sym->start); > + u64 right = unmap_ip(node->map, > + node->sym->start);
So, in the above, you say that cnode->ms.map or node->map may be NULL, right? But then both are asking for a sym->start (which is a relative address, it came from a symtab), and furthermore, for cnode->ms.sym to be not NULL means that cnode->ms.map is not NULL, after all cnode->ms.sym came from a dso__find_symbol(cnode->ms.map->dso).
Ditto for node->sym/node->map.
> match = match_chain_addresses(left, right); > break; > } > @@ -713,7 +719,9 @@ static enum match_result match_chain(struct > callchain_cursor_node *node, > __fallthrough; > case CCKEY_ADDRESS: > default: > - match = match_chain_addresses(cnode->ip, node->ip); > + match = match_chain_addresses(unmap_ip(cnode->ms.map, > + cnode->ip), > + unmap_ip(node->map, node->ip));
Here I need to look further, to see what kind of address cnode->ip is, my expectation is that it is a absolute address, so no need for unmapping, will check.
- Arnaldo
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