[FUG-BR] Valor aconselhavel para variável HZ

[Edinilson - ATINET]

>----- Original Message ----- 
>From: "Paulo Henrique - BSDs" <paulo.rddck at bsd.com.br>
>To: ""Lista Brasileira de Discussão sobre FreeBSD (FUG-BR)"" 
><freebsd at fug.com.br>
>Sent: Wednesday, November 05, 2014 3:58 PM
>Subject: [FUG-BR] Valor aconselhavel para variável HZ
> Saudações,
>
> Gostaria de saber se alguém trabalha com a variável HZ com o valor 
> superior a 2000, caso sim o ambiente fica estável, há uma melhora no 
> desempenho do sistema e da rede ?
> Sei que a mesma interfere quanto ao uso da bateria em portáteis contudo a 
> duvida é restrita a servidores.
> Aumentar o valor da mesma em um servidor com 12 Cores / 24 Threads com 
> 32Gbytes de ram melhorará o desempenho.
> Abaixo tem os dados do sistema atualmente.
> O HZ do sistema está em 2000.
>
> uname -a
> FreeBSD xxxxx 10.0-STABLE FreeBSD 10.0-STABLE #0 r269344: Thu Jul 31 
> 14:39:46 BRT 2014
> netstat -m
> yyyyyyy at xxxxx:/usr/obj/usr/src/sys/XXXXXXXXXXX amd64
> 11204/15571/26775 mbufs in use (current/cache/total)
> 1023/9825/10848/2036062 mbuf clusters in use (current/cache/total/max)
> 1023/9512 mbuf+clusters out of packet secondary zone in use 
> (current/cache)
> 0/548/548/1018031 4k (page size) jumbo clusters in use 
> (current/cache/total/max)
> 0/0/0/301638 9k jumbo clusters in use (current/cache/total/max)
> 0/0/0/169671 16k jumbo clusters in use (current/cache/total/max)
> 4847K/25734K/30581K bytes allocated to network (current/cache/total)
> 0/0/0 requests for mbufs denied (mbufs/clusters/mbuf+clusters)
> 0/0/0 requests for mbufs delayed (mbufs/clusters/mbuf+clusters)
> 0/0/0 requests for jumbo clusters delayed (4k/9k/16k)
> 0/0/0 requests for jumbo clusters denied (4k/9k/16k)
> 0 requests for sfbufs denied
> 0 requests for sfbufs delayed
> 9966280 requests for I/O initiated by sendfile
>
> uptime
> 15:47 up 86 days, 19:40, 1 user, load averages: 8,15 8,86 9,27
>
>
> Alguns tunnings que já foi feito no sistema.
>
> # $FreeBSD: stable/10/etc/sysctl.conf 112200 2003-03-13 18:43:50Z mux $
> #
> # This file is read when going to multi-user and its contents piped thru
> # ``sysctl'' to adjust kernel values. ``man 5 sysctl.conf'' for details.
> #
>
> # Uncomment this to prevent users from seeing information about processes 
> that
> # are being run under another UID.
> #security.bsd.see_other_uids=0
>
> kern.maxfiles=1000000
>
> # Otimizacoes de rede.
> #kern.ipc.nmbclusters=131072 # 128Mb para buffer de rede - Ficou instavel 
> valor definido pelo sistema.
> kern.ipc.maxsockbuf=33554432
> net.inet.tcp.sendbuf_max=33554432
> net.inet.tcp.recvbuf_max=33554432
> net.inet.tcp.sendspace=1048576 # default 65536
> net.inet.tcp.recvspace=1048576 # default 32768
> net.inet.tcp.sendbuf_inc=1048576 # 8192 default
> net.inet.tcp.recvbuf_inc=1048576 # 16384 default
> kern.ipc.somaxconn=4096 # 128 default
> net.inet.tcp.syncache.rexmtlimit=1
> net.inet.tcp.syncookies=1
>
> # COnfigura▒▒es de Seguran▒a
> # General Security and DoS mitigation.
> net.inet.ip.check_interface=1 # verify packet arrives on correct interface
> net.inet.ip.portrange.randomized=1 # randomize outgoing upper ports
> net.inet.ip.process_options=0 # IP options in the incoming packets will be 
> ignored
> net.inet.ip.random_id=1 # assign a random IP_ID to each packet leaving the 
> system
> net.inet.ip.redirect=0 # do not send IP redirects
> net.inet.ip.accept_sourceroute=0 # drop source routed packets since they 
> can not be trusted
> net.inet.ip.sourceroute=0 # if source routed packets are accepted the 
> route data is ignored
> #net.inet.ip.stealth=1 # do not reduce the TTL by one(1) when a packets 
> goes through the firewall
> net.inet.icmp.bmcastecho=0 # do not respond to ICMP packets sent to IP 
> broadcast addresses
> net.inet.icmp.maskfake=0 # do not fake reply to ICMP Address Mask Request 
> packets
> net.inet.icmp.maskrepl=0 # replies are not sent for ICMP address mask 
> requests
> net.inet.icmp.log_redirect=0 # do not log redirected ICMP packet attempts
> net.inet.icmp.drop_redirect=1 # no redirected ICMP packets
> #net.inet.icmp.icmplim=50 # 50 ICMP packets per second. a reasonable 
> number for a small office.
> #net.inet.tcp.delayed_ack=1 # always employ delayed ack, 6 packets get 1 
> ack to increase bandwidth
> net.inet.tcp.drop_synfin=1 # SYN/FIN packets get dropped on initial 
> connection
> net.inet.tcp.ecn.enable=1 # explicit congestion notification (ecn) 
> warning: some ISP routers abuse it
> net.inet.tcp.fast_finwait2_recycle=1 # recycle FIN/WAIT states quickly 
> (helps against DoS, but may cause false RST)
> net.inet.tcp.icmp_may_rst=0 # icmp may not send RST to avoid spoofed 
> icmp/udp floods
> net.inet.tcp.maxtcptw=15000 # max number of tcp time_wait states for 
> closing connections
> net.inet.tcp.msl=5000 # 5 second maximum segment life waiting for an ACK 
> in reply to a SYN-ACK or FIN-ACK
> net.inet.tcp.path_mtu_discovery=0 # disable MTU discovery since most ICMP 
> packets are dropped by others
> net.inet.tcp.rfc3042=0 # disable the limited transmit mechanism which can 
> slow burst transmissions
> #net.inet.tcp.sack.enable=1 # sack disabled? 
> http://www.ibm.com/developerworks/linux/library/l-tcp-sack/index.html
> net.inet.udp.blackhole=1 # drop udp packets destined for closed sockets
> net.inet.tcp.blackhole=2 # drop tcp packets destined for closed ports
> #net.route.netisr_maxqlen=4096 # route queue length defaults 4096 (rtsock 
> using "netstat -Q")
> security.bsd.see_other_uids=0 # hide processes for root from user uid's
>
> ## Configuracoes de envio
>
> net.local.stream.sendspace=164240
> net.local.stream.recvspace=164240
>
> ## Configuracoes contra spoof
>
> net.inet.ip.rtexpire=60 # 3600 secs
> net.inet.ip.rtminexpire=2 # 10 secs
> net.inet.ip.rtmaxcache=1024 # 128 entries
>
> Qualquer orientação é bem vinda.
>

Ate o FreeBSD 7 eu ate que me preocupava em ficar mexendo no hz. Apos isto, 
e com estas interfaces de rede modernas da Intel, nao me preocupo mais (nem 
com hz nem com polling) pois PARECE nao mudar muito coisa.

Veja uma discussao de 2005 sobre o hz onde ja se discutia isto:
http://lists.freebsd.org/pipermail/freebsd-questions/2005-April/083482.html

e veja tambem este link, na parte onde esta o hz o que ele diz:
https://calomel.org/freebsd_network_tuning.html


Edinilson
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