From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <499D8065.2020009@domain.hid> Date: Thu, 19 Feb 2009 16:53:09 +0100 From: Jan Kiszka 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> <499D76AE.2090309@domain.hid> In-Reply-To: <499D76AE.2090309@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: rpm@xenomai.org Cc: xenomai-core Philippe Gerum wrote: > 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. > > Nope. An individual 4k request is going to pull 8 x 512 bytes pages from the > stack pool, not more. Yeah, I see. The only "overhead" here was already paid via the pagemap. > > Reminds me of TLSF - if I only had the time... :) > > It looks like working properly for -solo. I think to remember your concerns were more about missing fragmentation, size overhead and performance comparisons. A working version for standard Xenomai was already available at that time (maybe not for all archs, but that is surely quickly fixed). Jan -- Siemens AG, Corporate Technology, CT SE 2 Corporate Competence Center Embedded Linux