From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: 46% performance drop with change in glibc Date: Wed, 02 Nov 2005 14:37:57 -0600 Message-ID: <436923A5.2060102@us.ibm.com> References: <200511021310.51926.habanero@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200511021310.51926.habanero@us.ibm.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: habanero@us.ibm.com Cc: xen-devel List-Id: xen-devel@lists.xenproject.org Hi Andrew, My immediate guess would be TLS emulation. Do you not disable TLS on FC4? Regards, Anthony Liguori Andrew Theurer wrote: >I have been trying to track down a xen performance regression from Fedora >core3 to core4 i386 and I think I might have narrowed it down. First some >background info: I ran the SDET benchmark [1] and discovered that we have >about a 45% regression after upgrading to Fedora core 4. I noticed >xenoprofile showed ~20% in error_code on FC4, but only ~3.5% in error_code >(should we even have 3%?!?) on FC3. At first I thought the change to gcc-4 >might have something to do with it, so I tried gcc4 on FC3 -no regression. >I noticed glibc was also different, so I upgraded FC3 from 2.3.3 to 2.3.5 >-bingo. I am not sure what about glibc is causing this, but here are the >two profiles: > >fc3 with glic-2.3.3: > >samples % app name symbol name >56097 22.8770 cc1 (no symbols) >22780 9.2900 troff (no symbols) >8646 3.5259 xen-unstable-syms error_code >7822 3.1899 grotty (no symbols) >5283 2.1545 libc-2.3.3.so _int_malloc >4914 2.0040 vmlinux-2.6.12-xen0-up buffered_rmqueue >4453 1.8160 bash (no symbols) >4372 1.7830 xen-unstable-syms get_page_from_l1e >3492 1.4241 xen-unstable-syms put_page_from_l1e >3338 1.3613 vmlinux-2.6.12-xen0-up system_call >3040 1.2397 xen-unstable-syms hypercall >2801 1.1423 xen-unstable-syms alloc_page_type >2799 1.1415 vmlinux-2.6.12-xen0-up zap_pte_range >2798 1.1411 libstdc++.so.6.0.3 (no symbols) >2761 1.1260 libc-2.3.3.so vfprintf >2637 1.0754 vmlinux-2.6.12-xen0-up do_no_page >2555 1.0420 libc-2.3.3.so __i686.get_pc_thunk.bx >2548 1.0391 vmlinux-2.6.12-xen0-up page_fault > >fc3 with glibc-2.3.5: > >samples % app name symbol name >133404 22.7469 xen-unstable-syms error_code >31411 5.3559 libc-2.3.5.so malloc >30316 5.1692 troff (no symbols) >20632 3.5180 libc-2.3.5.so vfprintf >16626 2.8349 xen-unstable-syms gpf_emulate_4gb >10639 1.8141 xen-unstable-syms do_general_protection >10105 1.7230 grotty (no symbols) >9837 1.6773 libc-2.3.5.so getwchar >8057 1.3738 xen-unstable-syms decode_register >7347 1.2527 libc-2.3.5.so iswgraph >7114 1.2130 vmlinux-2.6.12-xen0-up buffered_rmqueue >6926 1.1810 cc1 is_attribute_p >6679 1.1388 libc-2.3.5.so _int_malloc >6350 1.0827 xen-unstable-syms fixup_seg >5673 0.9673 xen-unstable-syms get_baselimit >5039 0.8592 bash (no symbols) >4957 0.8452 xen-unstable-syms get_page_from_l1e >4908 0.8369 xen-unstable-syms put_page_from_l1e >4576 0.7803 ld-2.3.5.so do_lookup_x >4322 0.7370 xen-unstable-syms hypercall >3915 0.6676 vmlinux-2.6.12-xen0-up system_call > >I assume something related to gpf_emulate_4gb... >Anyone have an idea why this would cause such a regression? > >-Andrew > > >[1] SDET described here: >http://www.spec.org/osg/sdm91/ > >_______________________________________________ >Xen-devel mailing list >Xen-devel@lists.xensource.com >http://lists.xensource.com/xen-devel > > >