.. I have compiled (with initrd) xen 3.3 from source tar ball following the README file under centos 5.2. xen kernel boots fine but my system (2 cores, 2.0 GHZ, 1GB RAM) is slow with a warning message. *************************************************************** *************************************************************** ** WARNING: Currently emulating unsupported memory accesses ** ** in /lib/tls glibc libraries. The emulation is ** ** slow. To ensure full performance you should ** ** install a ''xen-friendly'' (nosegneg) version of ** ** the library, or disable tls support by executing ** ** the following as root: ** ** mv /lib/tls /lib/tls.disabled ** ** Offending process: modprobe (pid=849) ** *************************************************************** *************************************************************** Is my system slow due to this tls warning? or I can ignore the warning. similar thread is here http://lists.xensource.com/archives/html/xen-users/2006-04/msg00545.html. But thats not working for me. May be I am compiling from source. Thanks Paras. I _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi Paras, On Tue, 2008-11-25 at 12:18 -0600, Paras pradhan wrote:> I have compiled (with initrd) xen 3.3 from source tar ball following > the README file under centos 5.2. xen kernel boots fine but my system > (2 cores, 2.0 GHZ, 1GB RAM) is slow with a warning message. > > *************************************************************** > *************************************************************** > ** WARNING: Currently emulating unsupported memory accesses ** > ** in /lib/tls glibc libraries. The emulation is ** > ** slow. To ensure full performance you should ** > ** install a ''xen-friendly'' (nosegneg) version of ** > ** the library, or disable tls support by executing ** > ** the following as root: ** > ** mv /lib/tls /lib/tls.disabled ** > ** Offending process: modprobe (pid=849) ** > *************************************************************** > *************************************************************** > > Is my system slow due to this tls warning? or I can ignore the > warning.If you have installed Xen friendly libc (usually called libc6-xen), there is no reason to disable tls. Some programs on your system are statically linked. Meaning, when they are compiled, the whole C library becomes part of the program. Anything that was compiled this way on a system that does not have xen-friendly libc is going to throw that warning and yes, it is harmless. Programs like ''modprobe'', ''init'' and others are sometimes statically linked. Its done because in some special setups, these programs need to run before any file systems are actually mounted. For that to work, the programs need to have all libraries linked in .. because /usr/lib and /lib might not be available yet when they run. On most newer distros, this is not the case any longer. If you ever see a threading service (i.e. apache) throw this warning, its a problem because it means the service was statically linked and is not using your xen friendly libc (the shared objects in /lib/tls). You are very unlikely to ever encounter that. The warning is perfectly safe to ignore otherwise. If you really need to make it go away, obtain the source packages to sysvinit, module-tools, etc and compile them against your xen friendly libc. Really, there is no need to do this. Cheers, --Tim _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Paras pradhan wrote:> I have compiled (with initrd) xen 3.3 from source tar ball following > the README file under centos 5.2. xen kernel boots fine but my system > (2 cores, 2.0 GHZ, 1GB RAM) is slow with a warning message. > > *************************************************************** > *************************************************************** > ** WARNING: Currently emulating unsupported memory accesses ** > ** in /lib/tls glibc libraries. The emulation is ** > ** slow. To ensure full performance you should ** > ** install a ''xen-friendly'' (nosegneg) version of ** > ** the library, or disable tls support by executing ** > ** the following as root: ** > ** mv /lib/tls /lib/tls.disabled ** > ** Offending process: modprobe (pid=849) ** > *************************************************************** > *************************************************************** > > Is my system slow due to this tls warning? or I can ignore the warning.As it says in http://lists.xensource.com/archives/html/xen-users/2006-04/msg00594.html (and corrected slightly in the reply) you need to create a file called /etc/ld.so.conf.d/nosegneg.conf that contains something like this: # This directive teaches ldconfig to search in nosegneg subdirectories # and cache the DSOs there with extra bit 0 set in their hwcap match # fields. In Xen guest kernels, the vDSO tells the dynamic linker to # search in nosegneg subdirectories and to match this extra hwcap bit # in the ld.so.cache file. hwcap 0 nosegneg The file must have a ".conf" suffix and the critical line is that last one -- the rest is commentary. I copied it wholesale from, I think, a Fedora 8 machine where I had installed the xen rpms. You don''t need to install any special libc and ignore comments from people about renaming /lib/tls to /lib/tls.disabled. The former is because the CentOS (aka RHEL and also Fedora) glibc already has the necessary changes, the latter because it''s an empty directory and renaming it to stop the runtime linker finding stuff doesn''t help :-) Also ignore people telling you that modprobe and init are statically linked on CentOS, they''re not. But for anyone else reading this in the archives -- remember that all of the above is CentOS/RHEL/Fedora specific: different distros do things differently. jch _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Wed, 2008-11-26 at 10:31 +0000, John Haxby wrote:> Also ignore people telling you that modprobe and init are statically > linked on CentOS, they''re not.Which version of CentOS?> But for anyone else reading this in the archives -- remember that all of > the above is CentOS/RHEL/Fedora specific: different distros do things > differently.And everyone uses RHEL/CentOS? Nobody uses Slackware? Search the archives and you will find that this was indeed the case. Or must I boot every distro since Xen 3.x and paste the output of ldd? The fact remains, the warning is safe to ignore. Cheers, --Tim _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
John Haxby wrote:> > You don''t need to install any special libc and ignore comments from > people about renaming /lib/tls to /lib/tls.disabled. The former is > because the CentOS (aka RHEL and also Fedora) glibc already has the > necessary changes, the latter because it''s an empty directory and > renaming it to stop the runtime linker finding stuff doesn''t help :-) > > Also ignore people telling you that modprobe and init are statically > linked on CentOS, they''re not. > > But for anyone else reading this in the archives -- remember that all > of the above is CentOS/RHEL/Fedora specific: different distros do > things differently. >I re-read this. It sounds awful. The good people on this list (including those that also replied to this message) don''t deserve to be told to be ignored. Don''t ignore them ... just make sure that you don''t try to do things to your CentOS distribution that are applicable to Debian etc. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Tim Post wrote:> On Wed, 2008-11-26 at 10:31 +0000, John Haxby wrote: > > >> Also ignore people telling you that modprobe and init are statically >> linked on CentOS, they''re not. >> > > Which version of CentOS? > >The OP says "centos 5.2" which closely matches what I had. And I had exactly the same experience: the OS seemed very sluggish and that was fixed when I added the nosegneg stuff.>> But for anyone else reading this in the archives -- remember that all of >> the above is CentOS/RHEL/Fedora specific: different distros do things >> differently. >> > > And everyone uses RHEL/CentOS? Nobody uses Slackware? Search the > archives and you will find that this was indeed the case. Or must I boot > every distro since Xen 3.x and paste the output of ldd? > >No, of course not. I do know, though that I had a lot of trouble tracking down the right solution to the problem for CentOS because the majority of the advice in the lists is to rename the /lib/tls directory or to get a special version of glibc. I knew that wasn''t the case because, as luck would have it, I had a Fedora 8 machine with Xen installed on it and I hadn''t had any of the problems that I was seeing with my build on CentOS 5.2. But, of course, the OP was (is) using CentOS 5.2.> The fact remains, the warning is safe to ignore. >That''s quite true, although it is quite a nasty performance hit, at least on CentOS 5.2. jch _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Wed, 2008-11-26 at 11:32 +0000, John Haxby wrote:> The fact remains, the warning is safe to ignore. > > > That''s quite true, although it is quite a nasty performance hit, at > least on CentOS 5.2. > > jchYep, I saw the error but not the OS details, my bad. Its been a FAQ here so I just replied. Sorry! :) --Tim _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Wed, Nov 26, 2008 at 5:45 AM, Tim Post <echo@echoreply.us> wrote:> On Wed, 2008-11-26 at 11:32 +0000, John Haxby wrote: > > The fact remains, the warning is safe to ignore. > > > > > That''s quite true, although it is quite a nasty performance hit, at > > least on CentOS 5.2. > > > > jch > > Yep, I saw the error but not the OS details, my bad. Its been a FAQ here > so I just replied. > > Sorry! :) > > --Tim > >Since the workaround with disabling tls and adding nosegneg in ld did not work out, i managed to build glibc6-xen using glibc6 srpm file. Now i do not have that warning and my system is no longer slower now. Thanks for all the help Paras. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Paras pradhan wrote:> Since the workaround with disabling tls and adding nosegneg in ld did > not work out, i managed to build glibc6-xen using glibc6 srpm file. > Now i do not have that warning and my system is no longer slower now.That''s odd. I wonder why it didn''t work? Did you remember to run ldconfig after you''d made the change (and reboot to get everything restarted)? jch _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Wed, Nov 26, 2008 at 10:46 AM, John Haxby <john.haxby@oracle.com> wrote:> Paras pradhan wrote: > >> Since the workaround with disabling tls and adding nosegneg in ld did not >> work out, i managed to build glibc6-xen using glibc6 srpm file. Now i do not >> have that warning and my system is no longer slower now. >> > > That''s odd. I wonder why it didn''t work? Did you remember to run > ldconfig after you''d made the change (and reboot to get everything > restarted)? > > jch >Yes i did that.. Might be the problem with my centOS system since I have changed a lot manually. I will give a try in a fresh centos installation once more. Paras. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Wed, Nov 26, 2008 at 10:50 AM, Paras pradhan <pradhanparas@gmail.com>wrote:> > > On Wed, Nov 26, 2008 at 10:46 AM, John Haxby <john.haxby@oracle.com>wrote: > >> Paras pradhan wrote: >> >>> Since the workaround with disabling tls and adding nosegneg in ld did not >>> work out, i managed to build glibc6-xen using glibc6 srpm file. Now i do not >>> have that warning and my system is no longer slower now. >>> >> >> That''s odd. I wonder why it didn''t work? Did you remember to run >> ldconfig after you''d made the change (and reboot to get everything >> restarted)? >> >> jch >> > > > Yes i did that.. Might be the problem with my centOS system since I have > changed a lot manually. I will give a try in a fresh centos installation > once more. > > > Paras. >ok tested in a fresh install . did not work... both nosegneg and disabling tls. Thanks Paras. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Paras pradhan wrote:> ok tested in a fresh install . did not work... both nosegneg and > disabling tls.Well that''s bizarre. "hwcap 0 nosegneg" in a *.conf in /etc/ld.so.conf.d/foo.conf is exactly what the Xen CentOS and Fedora Xen installations do because it just tells the runtime linker to use the xen-friendly .so''s Can you confirm exactly what you did? These are the instructions I compiled for someone here recently, is this what you did? 1. Make doubly sure you''re running what you think you''re running (yes, I know, but ...) $ cat /etc/redhat-release CentOS release 5.2 (Final) 2. Create a suitable ld config file: $ echo "hwcap 0 nosegneg" > /etc/ld.so.conf.d/xen.conf It''s important that the file name ends ".conf" because /etc/ld.so.conf says "include ld.so.conf.d/*.conf" which means, of course that it will ignore any files in /etc/ld.so.conf.d that don''t end ".conf". 3. Run (as root) "/sbin/ldconfig" should take a while. 4. You may not need to do this, but reboot to make sure everything gets fresh shared libraries. 5. Double check that code is picking up the nosegneg libraries: $ ldd /sbin/modprobe linux-gate.so.1 => (0xb7f07000) libc.so.6 => /lib/i686/nosegneg/libc.so.6 (0x43271000) /lib/ld-linux.so.2 (0x00978000) I''m pretty sure this is write, I transcribed it from a scrap of paper :-) jch _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users