Date: Sat, 31 Oct 2015 15:56:25 +0700 From: Eugene Grosbein <eugen@grosbein.net> To: freebsd-mips@freebsd.org Subject: Re: CPU underload Message-ID: <56348239.3050701@grosbein.net> In-Reply-To: <56348063.3090508@grosbein.net> References: <56348063.3090508@grosbein.net>
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On 31.10.2015 15:48, Eugene Grosbein wrote: > Hi! > > I'm trying to get familiar with PMC and uncover reason of MIPS32 > CPU being underloaded - about 50% - while performing traffic forwarding. > > It seems, kernel code abuses DELAY function as "pmcstat -S instructions -T" shows: [skip] > And why so heavy usage of _libmd_SHA256_Transf ? Well, it seems to be kern.random.harvest is guity for SHA256 abuse. I've set sysctl kern.random.harvest.mask=0 and now it' gone: PMC: [INSTR_EXECUTED] Samples: 7490 (100.0%) , 0 unresolved %SAMP IMAGE FUNCTION CALLERS 4.6 kernel ip_fastforward 4.5 kernel memcpy 4.4 kernel DELAY 3.9 kernel arge_start_locked 3.8 kernel _bus_dmamap_load_buf 3.2 kernel ether_nh_input 3.1 kernel if_inc_counter 3.0 kernel arge_intr 3.0 kernel ether_output 2.9 kernel _bus_dmamap_sync 2.6 kernel bzero 2.6 kernel critical_enter 2.4 kernel critical_exit 2.3 kernel bus_dmamap_sync_buf 2.2 kernel _rw_runlock_cookie 2.1 kernel rn_match 1.9 kernel __rw_rlock 1.7 kernel netisr_dispatch_src 1.5 kernel spinlock_exit 1.5 kernel uma_zalloc_arg 1.5 kernel generic_bs_barrier 1.4 kernel _bus_dmamap_load_mbu 1.4 kernel arge_newbuf 1.4 kernel _rm_rlock 1.4 kernel m_adj 1.4 libpmc.so. pmclog_read 1.4 kernel mipsNN_pdcache_wb_ra 1.4 kernel arpresolve 1.3 kernel bcmp 1.3 kernel ether_demux 1.3 kernel mipsNN_pdcache_inv_r 1.3 kernel _bus_dmamap_unload 1.2 kernel uma_zfree_arg 1.2 kernel if_transmit 1.2 kernel bus_dmamap_load_mbuf 1.1 kernel _rm_runlock 1.0 kernel rtfree CONVERSION STATISTICS:oc1_fib #exec/elf 1 #samples/total 102761 #samples/unknown-function 2939 #callchain/dubious-frames 23 Still too many of DELAYs.
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