Re: Horrible L2 cache effects from kernel compile

Dave Hansen (haveblue@us.ibm.com)
Wed, 26 Feb 2003 19:24:13 -0800


Andi Kleen wrote:
> Other numbers may work better for your workload. Please test.
The whole post:
http://marc.theaimsgroup.com/?l=linux-kernel&m=104619044800608&w=2

The number of cycles in d_lookup increased by 10% with your patch. But,
it looks like lots of stuff was moving around, so I wouldn't take too
much stock in it.

% change 2.5.62 2.5.62-ak-dc
in cycles cycles(%oftot) cycles(%oftot)
+20.685% 6251(0.397%) 9834(0.603%) ext3_get_inode_loc
+13.296% 16183(1.027%) 21863(1.341%) try_to_wake_up
+10.560% 130566(8.283%) 166867(10.239%) d_lookup
+10.202% 12525(0.795%) 15892(0.975%) filemap_nopage
+5.991% 22127(1.404%) 25793(1.583%) schedule
+5.581% 8705(0.552%) 10064(0.618%) run_timer_softirq
+4.246% 7922(0.503%) 8917(0.547%) current_kernel_time
+4.116% 9196(0.583%) 10324(0.633%) __wake_up
+3.739% 21650(1.373%) 24123(1.480%) __find_get_block
+3.631% 7226(0.458%) 8034(0.493%) do_page_cache_readahead
+3.287% 72668(4.610%) 80239(4.923%) find_get_page
+2.857% 11435(0.725%) 12518(0.768%) strnlen_user
-2.184% 35107(2.227%) 34745(2.132%) .text.lock.inode
-2.200% 17129(1.087%) 16947(1.040%) __fput
-2.706% 28213(1.790%) 27632(1.695%) start_this_handle
-2.823% 36539(2.318%) 35703(2.191%) smp_apic_timer_interrupt
-3.668% 26074(1.654%) 25050(1.537%) load_balance
-3.844% 8367(0.531%) 8010(0.491%) find_vma
-4.340% 46642(2.959%) 44211(2.713%) scheduler_tick
-4.650% 9965(0.632%) 9387(0.576%) default_idle
-4.667% 14213(0.902%) 13384(0.821%) do_wp_page
-4.728% 13603(0.863%) 12794(0.785%) mark_offset_tsc
-4.815% 39748(2.522%) 37319(2.290%) __blk_queue_bounce
-6.545% 44437(2.819%) 40298(2.473%) x86_profile_hook
-6.991% 36113(2.291%) 32457(1.991%) __copy_from_user_ll
-7.660% 16275(1.032%) 14432(0.886%) may_open
-13.539% 28492(1.807%) 22432(1.376%) get_empty_filp
-16.257% 10334(0.656%) 7696(0.472%) file_move

-- 
Dave Hansen
haveblue@us.ibm.com

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