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([2804:1b3:a7c1:6157:e8dc:fc2f:3a83:26ff]) by smtp.gmail.com with ESMTPSA id iq2-20020a17090afb4200b002a9f707ec45sm11520174pjb.11.2024.04.23.11.47.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 Apr 2024 11:47:22 -0700 (PDT) Message-ID: <38773ae0-df62-467c-9ac0-b9fc6df6be14@linaro.org> Date: Tue, 23 Apr 2024 15:47:20 -0300 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] benchtests: Add difficult strstr needle for bruteforce algorithms To: Wilco Dijkstra , 'GNU C Library' References: Content-Language: en-US From: Adhemerval Zanella Netto Organization: Linaro In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-12.8 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On 18/04/24 10:03, Wilco Dijkstra wrote: > > Add another difficult needle to strstr that clearly shows the quadratic > complexity of bruteforce algorithms. > > OK for commit? LGTM, thanks. Reviewed-by: Adhemerval Zanella > > --- > > diff --git a/benchtests/bench-strstr.c b/benchtests/bench-strstr.c > index 9288ad16e963d5397419aa11263520d259d2d6b9..4b07d39a50b0e5e1f29743a258b05466099c1959 100644 > --- a/benchtests/bench-strstr.c > +++ b/benchtests/bench-strstr.c > @@ -352,6 +352,33 @@ test_hard_needle (json_ctx_t *json_ctx, size_t ne_len, size_t hs_len) > json_array_end (json_ctx); > json_element_object_end (json_ctx); > } > + > + /* Hard needle for bruteforce algorithms that match first few chars. */ > + { > + memset (hs, 'a', hs_len); > + for (int i = ne_len-1; i < hs_len; i += ne_len) > + hs[i] = 'b'; > + hs[hs_len] = 0; > + > + memset (ne, 'a', ne_len); > + ne[ne_len] = 0; > + > + json_element_object_begin (json_ctx); > + json_attr_uint (json_ctx, "len_haystack", hs_len); > + json_attr_uint (json_ctx, "len_needle", ne_len); > + json_attr_uint (json_ctx, "align_haystack", 0); > + json_attr_uint (json_ctx, "align_needle", 0); > + json_attr_uint (json_ctx, "fail", 1); > + json_attr_string (json_ctx, "desc", "Difficult bruteforce needle"); > + > + json_array_begin (json_ctx, "timings"); > + > + FOR_EACH_IMPL (impl, 0) > + do_one_test (json_ctx, impl, hs, ne, NULL); > + > + json_array_end (json_ctx); > + json_element_object_end (json_ctx); > + } > } > > static int >