From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Schreckenbach Date: Fri, 14 Mar 2003 12:33:12 +0000 Subject: Re: [Linux-ia64] page size > 16KB Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org yep, I'm doing some benchmark stuff with SAP/SAPDB and the performance is not as good as I expected. CONFIG_HUGETLB_PAGE=y is standard on a SLES8 kernel (2.4.19-SMP). I changed the page size from 16K to 64K and the performance increase was 2-3 percent. Changing Huge TLB Page Size" seems not to have any effect. I think I looked at almost all possible bottlenecks (database, SAP internal buffer, parameter of SAP's own memory layer etc.). Everything here seems to be OK, so the bottleneck must be the code produced by the gcc or the OS itselves. I'm calling readprofile -r before the run end readprofile after the run. These are the first lines of the output with a standard kernel: 2110715 cpu_idle 5996.3494 12975 sock_poll 81.0938 9523 fget 42.5134 36903 tcp_poll 33.9182 532 ia64_ret_from_syscall 16.6250 2477 remove_wait_queue 11.0580 2518 add_wait_queue 9.8359 7177 break_fault 8.3067 3210 find_vma_prev 6.2695 2143 unlock_page 5.5807 3051 __find_lock_page_helper 5.2969 3350 do_gettimeofday 4.7585 11122 sys_semop 4.4559 937 page_waitqueue 4.1830 741 __find_lock_page 3.8594 616 demine_args 3.8500 3322 try_atomic_semop 3.8449 673 shmem_nopage 3.5052 1489 update_queue 3.3237 13440 schedule 3.2558 2630 fput 3.1611 3914 do_select 3.0578 459 clear_page 2.8687 175 ia64_page_valid 2.7344 5166 try_to_wake_up 2.6038 310 __free_pages 2.4219 1053 __pollwait 2.3504 940 ipcperms 2.0982 1187 __wake_up 2.0608 with a kernel with 64K pagesize the output is: 2102011 cpu_idle 5971.6222 12492 sock_poll 78.0750 10001 fget 44.6473 27396 tcp_poll 25.1801 577 ia64_ret_from_syscall 18.0312 2468 remove_wait_queue 11.0179 9641 smp_call_function 10.3890 2455 add_wait_queue 9.5898 7334 break_fault 8.4884 10955 sys_semop 4.3890 2891 do_gettimeofday 4.1065 3358 try_atomic_semop 3.8866 548 demine_args 3.4250 13989 schedule 3.3888 1613 find_vma_prev 3.1504 3991 do_select 3.1180 2525 fput 3.0349 1299 update_queue 2.8996 636 page_waitqueue 2.8393 1492 __find_lock_page_helper 2.5903 247 flush_icache_range 2.5729 4868 try_to_wake_up 2.4536 146 wake_up_process 2.2812 1021 ipcperms 2.2790 429 shmem_nopage 2.2344 968 __pollwait 2.1607 137 ia64_page_valid 2.1406 819 unlock_page 2.1328 402 __find_lock_page 2.0938 I'm far from being an expert in kernel stuff, but I don't see a big difference. Jan Grant Grundler wrote: > On Wed, Mar 12, 2003 at 09:40:55AM -0800, David Mosberger wrote: > >>On the other hand, the performance measurements I have done with 64KB >>page size suggested that the page size could become the sweet-spot >>much sooner than I had expected. > > > > For Oracle/SAP, wouldn't "HUGETLB_PAGE" cover most of the same problems? > I suspect that's all Jan (SAP) might need but don't know exactly what > problem Jan is trying to address. Jan? > > grant > > _______________________________________________ > Linux-IA64 mailing list > Linux-IA64@linuxia64.org > http://lists.linuxia64.org/lists/listinfo/linux-ia64 > -- _______________________________________________________________________ THE BEST RUN E-BUSINESSES RUN SAP _______________________________________________________________________ Jan Schreckenbach email: Jan.Schreckenbach@sap.com SAP AG Walldorf/Baden, Germany Phone: +49 6227 7-47474 LinuxLab Fax : +49 6227 78-31414 SAP LinuxLab support address: linux@sap.com