Hi.. I was going through wiki page of Credit Scheduler which says - " The scheduling decision is the common path of the scheduler and is therefore designed to be light weight and efficient. No accounting takes place in this code path. " So where does the accounting process takes place. exctaly by which way accounting for CPU, different IO device usage is done. With the complex architecture of Xen, how does this accounting process is carried out? thanks, -Rahul --------------------------------- Heres a new way to find what you''re looking for - Yahoo! Answers --0-1218827237-1176116585=:12888 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Hi..<br><br>I was going through wiki page of Credit Scheduler which says -<br><span style="font-size: 10pt; font-family: "Times New Roman";">" The scheduling decision is the common path of the scheduler and is therefore designed to be light weight and efficient. No accounting takes place in this code path. " <br><br>So where does the accounting process takes place. exctaly by which way accounting for CPU, different IO device usage is done. With the complex architecture of Xen, how does this accounting process is carried out?<br><br>thanks,<br>-Rahul<br></span><p>  <hr size=1></hr> Heres a new way to find what you''re looking for - <a href="http://us.rd.yahoo.com/mail/in/yanswers/*http://in.answers.yahoo.com/">Yahoo! Answers</a> --0-1218827237-1176116585=:12888-- --===============1668530601=Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel --===============1668530601==--
On 09/04/07 12:03 +0100, rahul gundecha wrote:> > Hi.. > I was going through wiki page of Credit Scheduler which says - > " The scheduling decision is the common path of the scheduler and is > therefore designed to be light weight and efficient. No accounting > takes place in this code path. " > So where does the accounting process takes place. exctaly by which > way accounting for CPU, different IO device usage is done. With the > complex architecture of Xen, how does this accounting process is > carried out?The credit scheduler sets up a timer when it is initialized. It does process accounting during the timer service routine. The decision to schedule the next vcpu is done on a different code path, and is optimized to be as fast as possible. Mike -- Mike D. Day IBM LTC Cell: 919 412-3900 Sametime: ncmike@us.ibm.com AIM: ncmikeday Yahoo: ultra.runner PGP key: http://www.ncultra.org/ncmike/pubkey.asc _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
thanks alot Mike for kind reply. One more curiousity is how often a timer routine is called & how often scheduling code? It may be configurable interval as well, but then whats default value. I guess timer is called more frequently & call to scheduling routine is made less frquently and is called from timer itself. Can I get pointer to some reference where I will get to know how exactly this mechanism works. May be digging through code will be expensive option so I want to avoid it for a moment. thanks, -rahul "Mike D. Day" <ncmike@us.ibm.com> wrote: On 09/04/07 12:03 +0100, rahul gundecha wrote:> > Hi.. > I was going through wiki page of Credit Scheduler which says - > " The scheduling decision is the common path of the scheduler and is > therefore designed to be light weight and efficient. No accounting > takes place in this code path. " > So where does the accounting process takes place. exctaly by which > way accounting for CPU, different IO device usage is done. With the > complex architecture of Xen, how does this accounting process is > carried out?The credit scheduler sets up a timer when it is initialized. It does process accounting during the timer service routine. The decision to schedule the next vcpu is done on a different code path, and is optimized to be as fast as possible. Mike -- Mike D. Day IBM LTC Cell: 919 412-3900 Sametime: ncmike@us.ibm.com AIM: ncmikeday Yahoo: ultra.runner PGP key: http://www.ncultra.org/ncmike/pubkey.asc -Rahooooooooooooooool... exceptions are most common things to happen..... --------------------------------- Heres a new way to find what you''re looking for - Yahoo! Answers --0-1241446328-1176129653=:11334 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: 8bit thanks alot Mike for kind reply.<br><br>One more curiousity is how often a timer routine is called & how often scheduling code? It may be configurable interval as well, but then whats default value.<br>I guess timer is called more frequently & call to scheduling routine is made less frquently and is called from timer itself.<br><br>Can I get pointer to some reference where I will get to know how exactly this mechanism works. May be digging through code will be expensive option so I want to avoid it for a moment.<br><br>thanks,<br>-rahul<br><br><b><i>"Mike D. Day" <ncmike@us.ibm.com></i></b> wrote:<blockquote class="replbq" style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"> On 09/04/07 12:03 +0100, rahul gundecha wrote:<br>><br>> Hi..<br>> I was going through wiki page of Credit Scheduler which says -<br>> " The scheduling decision is the common path of the scheduler and is<br>> therefore designed to be light weight and efficient. No accounting<br>> takes place in this code path. "<br>> So where does the accounting process takes place. exctaly by which<br>> way accounting for CPU, different IO device usage is done. With the<br>> complex architecture of Xen, how does this accounting process is<br>> carried out?<br><br>The credit scheduler sets up a timer when it is initialized. It does<br>process accounting during the timer service routine.<br><br>The decision to schedule the next vcpu is done on a different code<br>path, and is optimized to be as fast as possible.<br><br>Mike<br><br>-- <br>Mike D. Day<br>IBM LTC<br>Cell: 919 412-3900<br>Sametime: ncmike@us.ibm.com AIM: ncmikeday Yahoo: ultra.runner<br>PGP key: http://www.ncultra.org/ncmike/pubkey.asc<br></blockquote><br><BR><BR><span style="color: rgb(0, 0, 191);"></span><img src="file:///C:/DOCUME%7E1/rahool/LOCALS%7E1/Temp/moz-screenshot.jpg" alt=""><img src="file:///C:/DOCUME%7E1/rahool/LOCALS%7E1/Temp/moz-screenshot-1.jpg" alt=""><img src="file:///C:/DOCUME%7E1/rahool/LOCALS%7E1/Temp/moz-screenshot-2.jpg" alt=""><a target="_blank" href="http://mail.google.com/mail/?realattid=f_ez7y22zo&attid=0.1&disp=inline&view=att&th=11146fbd76f18c5f"><img class="thi" src="http://mail.google.com/mail/?realattid=f_ez7y22zo&attid=0.1&disp=thd&view=att&th=11146fbd76f18c5f"></a><br><span style="color: rgb(0, 0, 255); font-style: italic;"></span><font size="4">-<span style="font-style: italic; color: rgb(0, 0, 191);">Rahooooooooooooooool...</span></font><br> <span style="color: rgb(0, 0, 191);">exceptions are most common things to happen..... <img src="http://us.i1.yimg.com/us.yimg.com/i/mesg/tsmileys2/03.gif"><br></span><p>  <hr size=1></hr> Heres a new way to find what you''re looking for - <a href="http://us.rd.yahoo.com/mail/in/yanswers/*http://in.answers.yahoo.com/">Yahoo! Answers</a> --0-1241446328-1176129653=:11334-- --===============0343396060=Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel --===============0343396060==--
On 09/04/07 15:40 +0100, rahul gundecha wrote:> > thanks alot Mike for kind reply. > One more curiousity is how often a timer routine is called & how often > scheduling code? It may be configurable interval as well, but then > whats default value. > I guess timer is called more frequently & call to scheduling routine > is made less frquently and is called from timer itself. > Can I get pointer to some reference where I will get to know how > exactly this mechanism works. May be digging through code will be > expensive option so I want to avoid it for a moment. > thanks, > -rahulThe timer is initialized in xen/common/sched_credit.c: static __init int csched_start_tickers(void) { struct csched_pcpu *spc; unsigned int cpu; for_each_online_cpu ( cpu ) { spc = CSCHED_PCPU(cpu); set_timer(&spc->ticker, NOW() + MILLISECS(CSCHED_MSECS_PER_TICK)); } return 0; } CSCHED_MSECS_PER_TICK is #defined as 10, so the accounting code runs every 10 ms - for each physical processor. Mike -- Mike D. Day IBM LTC Cell: 919 412-3900 Sametime: ncmike@us.ibm.com AIM: ncmikeday Yahoo: ultra.runner PGP key: http://www.ncultra.org/ncmike/pubkey.asc _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
> One more curiousity is how often a timer routine is called & how often scheduling code? It may be configurable interval as well, but then whats default value. > I guess timer is called more frequently & call to scheduling routine is made less frquently and is called from timer itself. > > Can I get pointer to some reference where I will get to know how exactly this mechanism works. May be digging through code will be expensive option so I want to avoid it for a moment.Your best bet is to study the code. The scheduler code is fairly readable. IIRC, the accounting code happens in two parts -- every 10ms, measurements are made, but only every 30ms the measurements are used to update accounting information. Read xen/common/sched_credit.c Diwaker -- Web/Blog/Gallery: http://floatingsun.net/blog _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
thanks alot Diwaker & Mike from your kind replies.. I will go through sched_credit.c as well.. regards, -Rahul Diwaker Gupta <diwaker.lists@gmail.com> wrote: > One more curiousity is how often a timer routine is called & how often scheduling code? It may be configurable interval as well, but then whats default value.> I guess timer is called more frequently & call to scheduling routine is made less frquently and is called from timer itself. > > Can I get pointer to some reference where I will get to know how exactly this mechanism works. May be digging through code will be expensive option so I want to avoid it for a moment.Your best bet is to study the code. The scheduler code is fairly readable. IIRC, the accounting code happens in two parts -- every 10ms, measurements are made, but only every 30ms the measurements are used to update accounting information. Read xen/common/sched_credit.c Diwaker -- Web/Blog/Gallery: http://floatingsun.net/blog -Rahooooooooooooooool... exceptions are most common things to happen..... --------------------------------- Check out what you''re missing if you''re not on Yahoo! Messenger _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Liang Yang
2007-Apr-11 19:04 UTC
[Xen-devel] XenOProfile may have the conflict with SATA AHCI mode.
Hi, I notice this issue recently when I''m using XenOProfile with the latest Xen-unstable repository. I have several SATA disks to hose several guest domains. For the performance purpose, I want to use the on-board AHCI mode so each SATA disk has its own data transfer channel. However, I found XenOProfile has some conflict with AHCI mode as Xen will boot into kernel panic with weird mount errors after XenOProfile is enabled. The problem is gone when I set SATA mode to compatible in BIOS (i.g. IDE emulation mode). Regards, Liang _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Ian Pratt
2007-Apr-11 19:17 UTC
RE: [Xen-devel] XenOProfile may have the conflict with SATA AHCI mode.
> I notice this issue recently when I''m using XenOProfile with thelatest> Xen-unstable repository. I have several SATA disks to hose severalguest> domains. For the performance purpose, I want to use the on-board AHCI > mode > so each SATA disk has its own data transfer channel. However, I found > XenOProfile has some conflict with AHCI mode as Xen will boot into > kernel > panic with weird mount errors after XenOProfile is enabled. Theproblem> is > gone when I set SATA mode to compatible in BIOS (i.g. IDE emulation > mode).XenOProfile is the only thing that uses NMIs, but I''ve no idea why that would interfere with the SATA controller. If you were seing the issue round the other way I''d suspect something dodgy with the BIOS''es SMM mode. Might still be worth checking for a BIOS upgrade. Ian _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Santos, Jose Renato G
2007-Apr-11 21:36 UTC
RE: [Xen-devel] XenOProfile may have the conflict with SATA AHCI mode.
> -----Original Message----- > From: xen-devel-bounces@lists.xensource.com > [mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of Ian Pratt > Sent: Wednesday, April 11, 2007 12:18 PM > To: Liang Yang; xen-devel@lists.xensource.com > Subject: RE: [Xen-devel] XenOProfile may have the conflict > with SATA AHCI mode. > > > I notice this issue recently when I''m using XenOProfile with the > latest > > Xen-unstable repository. I have several SATA disks to hose several > guest > > domains. For the performance purpose, I want to use the > on-board AHCI > > mode so each SATA disk has its own data transfer channel. > However, I > > found XenOProfile has some conflict with AHCI mode as Xen will boot > > into kernel panic with weird mount errors after XenOProfile is > > enabled. The > problem > > is > > gone when I set SATA mode to compatible in BIOS (i.g. IDE > emulation > > mode). > > XenOProfile is the only thing that uses NMIs, but I''ve no > idea why that would interfere with the SATA controller. >I don''t know how XenOprofile could be interfering with SATA controller either. The only possible explanation I can think of is that the NMI interrupts are disrupting some time sensitive code in the SATA driver, but I do not know much about SATA. Maybe someone more familiar with SATA can comment. Do you see the same behavior runing Oprofile in vanila linux? What is the parameters you use to start oprofile? Renato.> If you were seing the issue round the other way I''d suspect > something dodgy with the BIOS''es SMM mode. Might still be > worth checking for a BIOS upgrade. > > Ian > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Liang Yang
2007-Apr-12 22:23 UTC
Re: [Xen-devel] XenOProfile may have the conflict with SATA AHCI mode.
I once thought maybe the problem is caused by the failure of loading AHCI driver. So I added --preload=AHCI when building ramdisk for Xen after XenOProfiling is enabled. However, Xen still booted into kernel panic with weird mount errors. I used some patch for XenOProfile nmi_int.c to make it work on Intel core 2 based processors. I notice Xen also updated nmi_int.c a couple of days ago to make XenOProfile recognize Intel core 2 based processors. I hope the problem is not caused by the updates of nmi_int.c. BTW, The BIOS is already flashed to the latest I could get. Liang ----- Original Message ----- From: "Ian Pratt" <Ian.Pratt@cl.cam.ac.uk> To: "Liang Yang" <multisyncfe991@hotmail.com>; <xen-devel@lists.xensource.com> Sent: Wednesday, April 11, 2007 12:17 PM Subject: RE: [Xen-devel] XenOProfile may have the conflict with SATA AHCI mode.> I notice this issue recently when I''m using XenOProfile with thelatest> Xen-unstable repository. I have several SATA disks to hose severalguest> domains. For the performance purpose, I want to use the on-board AHCI > mode > so each SATA disk has its own data transfer channel. However, I found > XenOProfile has some conflict with AHCI mode as Xen will boot into > kernel > panic with weird mount errors after XenOProfile is enabled. Theproblem> is > gone when I set SATA mode to compatible in BIOS (i.g. IDE emulation > mode).XenOProfile is the only thing that uses NMIs, but I''ve no idea why that would interfere with the SATA controller. If you were seing the issue round the other way I''d suspect something dodgy with the BIOS''es SMM mode. Might still be worth checking for a BIOS upgrade. Ian _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel