From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <444E8D7A.30900@domain.hid> Date: Tue, 25 Apr 2006 22:58:34 +0200 From: Philippe Gerum MIME-Version: 1.0 Subject: Re: [Xenomai-help] syslog safe? References: <20060425134048.D5934@domain.hid> <444E61F0.9000606@domain.hid> <20060425143711.E5934@domain.hid> In-Reply-To: <20060425143711.E5934@domain.hid> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kent Borg Cc: xenomai@xenomai.org Kent Borg wrote: > On Tue, Apr 25, 2006 at 07:52:48PM +0200, Philippe Gerum wrote: > >>No problem using it, but it will trigger an automatic switch to >>secondary mode in order to issue the right Linux syscalls. The thread >>will switch back to primary automatically again as soon as a (usually >>blocking) Xenomai syscall is issued. > > > And, looking at strace output, it appears that is a syslog() is too > low a priority to be logged it doesn't make a system call and so will > not drop us out of realtime. > > Do not trust strace there, it heavily relies on other glibc services, like buffered I/O, which might issue syscalls under various conditions. For instance, internal mutex locking might cause a syscall to deal with any contended request, or malloc called indirectly might ask for extending the caller's data segment, and so on. Additionally, some syslog flags, like LOG_CONS, do cause file I/O. -- Philippe.