From patchwork Fri Jul 1 18:31:18 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Siddhesh Poyarekar X-Patchwork-Id: 13557 Received: (qmail 62991 invoked by alias); 1 Jul 2016 18:31:52 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 62870 invoked by uid 89); 1 Jul 2016 18:31:51 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=0.5 required=5.0 tests=AWL, BAYES_50, RCVD_IN_DNSWL_NONE, SPF_NEUTRAL autolearn=no version=3.3.2 spammy=HX-Envelope-From:sk:siddhes, H*F:U*siddhesh, 1166, colon X-HELO: homiemail-a69.g.dreamhost.com From: Siddhesh Poyarekar To: libc-alpha@sourceware.org Subject: [PATCH 2/2] Initialize tunable list with the GLIBC_TUNABLES environment variable Date: Sat, 2 Jul 2016 00:01:18 +0530 Message-Id: <1467397878-11514-3-git-send-email-siddhesh@sourceware.org> In-Reply-To: <1467397878-11514-1-git-send-email-siddhesh@sourceware.org> References: <1467397878-11514-1-git-send-email-siddhesh@sourceware.org> Read tunables values from the users using the GLIBC_TUNABLES environment variable. The value of this variable is a colon-separated list of name=value pairs. So a typical string would look like this: GLIBC_TUNABLES=glibc.malloc.mmap_threshold=2048:glibc.malloc.trim_threshold=1024 * elf/dl-tunables.c: Include string.h. (parse_tunables): New function. (GLIBC_TUNABLES): New macro. (__tunables_init): Use it. --- elf/dl-tunables.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c index 8a26dfc..04d1d52 100644 --- a/elf/dl-tunables.c +++ b/elf/dl-tunables.c @@ -22,10 +22,13 @@ #include #include #include +#include #define TUNABLES_INTERNAL 1 #include "dl-tunables.h" +#define GLIBC_TUNABLES "GLIBC_TUNABLES" + /* Compare environment names, bounded by the name hardcoded in glibc. */ static bool is_name (const char *orig, const char *envname) @@ -104,6 +107,66 @@ tunable_initialize (tunable_t *cur) } } +static void +parse_tunables (char *tunestr) +{ + if (tunestr == NULL || *tunestr == '\0') + return; + + char *p = tunestr; + + while (true) + { + char *name = p; + size_t len = 0; + + /* First, find where the name ends. */ + while (p[len] != '=' && p[len] != ':' && p[len] != '\0') + len++; + + /* If we reach the end of the string before getting a valid name-value + pair, bail out. */ + if (p[len] == '\0') + return; + + /* We did not find a valid name-value pair before encountering the + colon. */ + if (p[len]== ':') + { + p += len + 1; + continue; + } + + p += len + 1; + + char *value = p; + len = 0; + + while (p[len] != ':' && p[len] != '\0') + len++; + + char end = p[len]; + p[len] = '\0'; + + /* Add the tunable if it exists. */ + for (size_t i = 0; i < sizeof (tunable_list) / sizeof (tunable_t); i++) + { + if (is_name (tunable_list[i].name, name)) + { + /* Tunable values take precedence over the env_alias. */ + tunable_list[i].strval = value; + tunable_initialize (&tunable_list[i]); + break; + } + } + + if (end == ':') + p += len + 1; + else + return; + } +} + /* Initialize the tunables list from the environment. For now we only use the ENV_ALIAS to find values. Later we will also use the tunable names to find values. */ @@ -116,6 +179,12 @@ __tunables_init (char **envp) while (get_next_env (&envp, &envname, &len, &envval)) { + if (is_name (GLIBC_TUNABLES, envname)) + { + parse_tunables (strdup (envval)); + continue; + } + for (int i = 0; i < sizeof (tunable_list) / sizeof (tunable_t); i++) { tunable_t *cur = &tunable_list[i];