From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jonas Pfefferle" Subject: Re: [PATCH] mem: warn if address hint is not respected Date: Wed, 03 Jan 2018 10:22:22 +0100 Message-ID: References: <1509440909-8068-1-git-send-email-jpf@zurich.ibm.com> <10656029.OGFJoE0f1c@xps> <55afaf0a-14cc-11b0-c7ec-21ea1bc2403f@intel.com> Mime-Version: 1.0 Content-Type: text/plain;charset=utf-8; format="flowed" Content-Transfer-Encoding: 8bit Cc: "dev@dpdk.org" , "jianfeng.tan@intel.com" , "Thomas Monjalon" To: "Xueming(Steven) Li" , "Burakov, Anatoly" Return-path: Received: from gozo.iway.ch (gozo.iway.ch [212.25.24.36]) by dpdk.org (Postfix) with ESMTP id CA64D1B1A6 for ; Wed, 3 Jan 2018 10:22:22 +0100 (CET) In-Reply-To: List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hi Xueming, Correct --base-virtaddr was introduced for that purpose. There are multiple reasons why the address layout of the secondary process might look different: reasons you mentioned in 2), ASLR etc. I believe there is no way to avoid this in real world use cases. The reason for this particular patch is that the address hint (--base-virtaddr) is sometimes not respected and the kernel falls back to just reserving any address it can find to satisfy the mapping (see discussion on the patch), i.e. effectively rendering --base-virtaddr useless. Regards, Jonas (new email address) On Tue, 26 Dec 2017 15:56:10 +0000 "Xueming(Steven) Li" wrote: > Hi Jonas, > > Seems you are trying to use --base-virtaddr to resolve address >conflicts > in secondary, I'm wondering how this happened and how to avoid it: > 1. what's your hugepage side? Hugepage mmap is size aligned, maybe >1G works? > 2. is there more libs loaded in secondary process or memory usage >before > EAL init? > 3. Since address allocated in one direction, I'm thinking to reserve >a > larger "hop" address space as MAP_ANONYMOUS, allocate hugepage, then >release > "hop". That essentially reserve an address space big enough for >secondary, > and most important the hop size is easy to estimate than >--base-virtaddr. > > Thanks, > Xueming(Steven) > >> -----Original Message----- >> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Jonas >>Pfefferle1 >> Sent: Wednesday, November 8, 2017 7:52 PM >> To: Burakov, Anatoly >> Cc: dev@dpdk.org; jianfeng.tan@intel.com; Thomas Monjalon >> >> Subject: Re: [dpdk-dev] [PATCH] mem: warn if address hint is not >>respected >> >> "Burakov, Anatoly" wrote on 11/07/2017 >> 02:54:24 >> PM: >> >> > From: "Burakov, Anatoly" >> > To: Thomas Monjalon >> > Cc: dev@dpdk.org, Jonas Pfefferle , >> jianfeng.tan@intel.com >> > Date: 11/07/2017 02:54 PM >> > Subject: Re: [dpdk-dev] [PATCH] mem: warn if address hint is not >> respected >> > >> > On 06-Nov-17 8:26 PM, Thomas Monjalon wrote: >> > > 31/10/2017 10:08, Jonas Pfefferle: >> > >> Print a warning if the --base-virtaddr hint is not respected >>since >> > >> this might lead to problems when mapping memory in the >>secondary >> > >> process. >> > >> >> > >> Signed-off-by: Jonas Pfefferle >> > > >> > > Anatoly, please review this patch. >> > > It does not seem to fix something, so it is candidate for 18.02. >> > > >> > >> > For some reason my Thunderbird ate the original email, so i'll >>reply >> > to this one. >> > >> > One nitpick would be that we're calling get_virtual_area many >>times >> > and it would probably be a good idea to make pagesize static and >>call >> > sysconf only once. Otherwise, >> >> We should address this in a separate patch and introduce a pagesize >> function for everyone to use. sysconf is used like this all over the >>place. >> >> > >> > Acked-by: Anatoly Burakov >> > >> > -- >> > Thanks, >> > Anatoly >> >