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Tue, 18 Mar 2025 02:52:22 -0700 (PDT) Received: from krava ([173.38.220.48]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5e816974016sm7484941a12.24.2025.03.18.02.52.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Mar 2025 02:52:22 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Tue, 18 Mar 2025 10:52:20 +0100 To: Sami Tolvanen Cc: dwarves@vger.kernel.org, acme@kernel.org, yonghong.song@linux.dev, ast@kernel.org, andrii@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, song@kernel.org, eddyz87@gmail.com, olsajiri@gmail.com, stephen.s.brennan@oracle.com, laura.nao@collabora.com, ubizjak@gmail.com, alan.maguire@oracle.com, xiyou.wangcong@gmail.com Subject: Re: [PATCH dwarves] btf_encoder: Filter out __gendwarfksyms_ptr_ Message-ID: References: <20250317222424.3837495-1-samitolvanen@google.com> Precedence: bulk X-Mailing-List: dwarves@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250317222424.3837495-1-samitolvanen@google.com> On Mon, Mar 17, 2025 at 10:24:24PM +0000, Sami Tolvanen wrote: > With CONFIG_GENDWARFKSYMS, __gendwarfksyms_ptr_ > variables are added to the kernel in EXPORT_SYMBOL() to ensure > DWARF type information is available for exported symbols in the > TUs where they're actually exported. These symbols are dropped > when linking vmlinux, but dangling references to them remain > in DWARF, which results in thousands of 0 address variables > that pahole needs to validate (since commit 9810758003ce > ("btf_encoder: Verify 0 address DWARF variables are in ELF > section")). > > Filter out symbols with the __gendwarfksyms_ptr_ name prefix in > filter_variable_name() instead of calling variable_in_sec() > for all of them. This reduces the time it takes to process > .tmp_vmlinux1 by ~77% on my test system: > > Before: 35.775 +- 0.121 seconds time elapsed ( +- 0.34% ) > After: 8.3516 +- 0.0407 seconds time elapsed ( +- 0.49% ) makes sense to me, I just can't reproduce the speedup could you please share your .config? thanks, jirka > > Signed-off-by: Sami Tolvanen > --- > btf_encoder.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/btf_encoder.c b/btf_encoder.c > index 1bde310..2bf7c59 100644 > --- a/btf_encoder.c > +++ b/btf_encoder.c > @@ -2239,6 +2239,7 @@ static bool filter_variable_name(const char *name) > X("__UNIQUE_ID"), > X("__tpstrtab_"), > X("__exitcall_"), > + X("__gendwarfksyms_ptr_"), > X("__func_stack_frame_non_standard_") > #undef X > }; > > base-commit: a0be596ae76c720d21eef257dec1cf2462130da1 > -- > 2.49.0.rc1.451.g8f38331e32-goog >