linux-kernel - Re: [PATCH 11/12] perf tools: Reuse shared eBPF dso objects

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Date:   Wed, 17 Apr 2019 09:35:32 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Jiri Olsa <jolsa@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Andi Kleen <ak@...ux.intel.com>,
        Song Liu <songliubraving@...com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: Re: [PATCH 11/12] perf tools: Reuse shared eBPF dso objects

On 16/04/19 7:01 PM, Jiri Olsa wrote:
> The eBPF program can be loaded multiple times
> with the same name (tag). We can share dso
> objects for those programs.

Doesn't a eBPF program get recompiled differently every time it is loaded?

> 
> Link: http://lkml.kernel.org/n/tip-3damf8vq1dryhtpbk5b06jpt@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  tools/perf/util/machine.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index d4aa44489011..a60653827891 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -23,6 +23,7 @@
>  #include "linux/hash.h"
>  #include "asm/bug.h"
>  #include "bpf-event.h"
> +#include "dso.h"
>  
>  #include "sane_ctype.h"
>  #include <symbol/kallsyms.h>
> @@ -699,11 +700,18 @@ static int machine__process_ksymbol_register(struct machine *machine,
>  
>  	map = map_groups__find(&machine->kmaps, event->ksymbol_event.addr);
>  	if (!map) {
> -		map = dso__new_map(event->ksymbol_event.name);
> -		if (!map)
> +		struct dso *dso;
> +
> +		dso = dsos__findnew(&machine->dsos, event->ksymbol_event.name);
> +		if (!dso)
>  			return -ENOMEM;
>  
> -		map->start = event->ksymbol_event.addr;
> +		map = map__new2(event->ksymbol_event.addr, dso);
> +		if (!map) {
> +			dso__put(dso);
> +			return -ENOMEM;
> +		}
> +
>  		map->end = map->start + event->ksymbol_event.len;
>  		map_groups__insert(&machine->kmaps, map);
>  	}
>