From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <499D6FC7.6010204@domain.hid> Date: Thu, 19 Feb 2009 15:42:15 +0100 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <499D359C.3060805@domain.hid> <499D3801.5040303@domain.hid> <499D3FE6.4030208@domain.hid> <499D5B0A.7020608@domain.hid> <499D5FC4.4030303@domain.hid> <499D67A6.7000301@domain.hid> <499D68A5.8020002@domain.hid> In-Reply-To: <499D68A5.8020002@domain.hid> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-core] XENO_OPT_SYS_STACKPOOLSZ vs. switchtest List-Id: "Xenomai life and development \(bug reports, patches, discussions\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: xenomai-core Jan Kiszka wrote: > Philippe Gerum wrote: >> Jan Kiszka wrote: >>> Gilles Chanteperdrix wrote: >>>> Jan Kiszka wrote: >>>>> Gilles Chanteperdrix wrote: >>>>>> Jan Kiszka wrote: >>>>>>> Hi Gilles, >>>>>>> >>>>>>> how much XENO_OPT_SYS_STACKPOOLSZ do I need to run switchtest for >>>>>>> default settings? At least on x86-64, the default 32K is not enough. >>>>>>> Unless we talk about GB ;), maybe it makes sense to adjust the default >>>>>>> size accordingly. >>>>>> It depends on the arguments you pass to switchtest. >>>>> None, ie. the default settings. >>>> Then 6 kernel-space tasks are created. Since switchtest is not the >>> 6*4 is 20k... Ah, the well-known allocator overhead, I guess. Will try >>> with >= 40k. >>> >> Actually, it is not really an overhead, but rather the fact that it wants at >> least two initially free pages per heap. > > That would make 22K. The problem is that the management overhead is > rounded up to another full page, requiring a 8K allocation per 4K > request. Reminds me of TLSF - if I only had the time... :) When allocating 4K, only 4K are allocated. I think the problem could rather be that you are running switchtest on a multi-cpu system, in which same the number of cpu tasks created is 6 by cpu. -- Gilles.