00000223.htm

一份很好的linux入门资料

Similar&nbsp;procedures&nbsp;are&nbsp;necessary&nbsp;to&nbsp;turn&nbsp;on&nbsp;the&nbsp;networking&nbsp;features.&nbsp;If&nbsp;<BR>
something&nbsp;appears&nbsp;to&nbsp;be&nbsp;broken,&nbsp;check&nbsp;the&nbsp;/proc/sys/net/ipv4&nbsp;directory.&nbsp;&quot;1&quot;&nbsp;<BR>
generally&nbsp;denotes&nbsp;enabled,&nbsp;while&nbsp;&quot;0&quot;&nbsp;stands&nbsp;for&nbsp;disabled.&nbsp;<BR>
If&nbsp;you&nbsp;use&nbsp;ISDN&nbsp;(as&nbsp;I&nbsp;sometimes&nbsp;do)&nbsp;you&nbsp;will&nbsp;have&nbsp;to&nbsp;recompile&nbsp;your&nbsp;kernel&nbsp;<BR>
on&nbsp;your&nbsp;machine&nbsp;with&nbsp;ISDN&nbsp;enabled.&nbsp;One&nbsp;major&nbsp;change&nbsp;is&nbsp;being&nbsp;introduced&nbsp;to&nbsp;<BR>
Linux'&nbsp;networking&nbsp;protocol.&nbsp;Whenever&nbsp;a&nbsp;packet&nbsp;was&nbsp;coming&nbsp;in&nbsp;from&nbsp;the&nbsp;<BR>
network,&nbsp;under&nbsp;older&nbsp;versions,&nbsp;all&nbsp;processes&nbsp;with&nbsp;an&nbsp;open&nbsp;socket&nbsp;connection&nbsp;<BR>
(i.e.&nbsp;executing&nbsp;a&nbsp;read()&nbsp;)&nbsp;were&nbsp;awoken&nbsp;by&nbsp;the&nbsp;kernel.&nbsp;Obviously&nbsp;only&nbsp;one&nbsp;<BR>
process&nbsp;could&nbsp;be&nbsp;the&nbsp;destination&nbsp;of&nbsp;that&nbsp;particular&nbsp;packet,&nbsp;therefore&nbsp;<BR>
making&nbsp;it&nbsp;an&nbsp;expensive&nbsp;operation&nbsp;to&nbsp;wake&nbsp;up&nbsp;all&nbsp;other,&nbsp;unconcerned&nbsp;<BR>
processes.&nbsp;As&nbsp;of&nbsp;2.4&nbsp;if&nbsp;the&nbsp;process&nbsp;registers&nbsp;with&nbsp;the&nbsp;kernel,&nbsp;only&nbsp;that&nbsp;<BR>
process&nbsp;will&nbsp;be&nbsp;woken&nbsp;up.&nbsp;<BR>
This&nbsp;will&nbsp;greatly&nbsp;benefit&nbsp;ftp&nbsp;and&nbsp;Web&nbsp;servers,&nbsp;after&nbsp;being&nbsp;appropriately&nbsp;<BR>
adapted&nbsp;for&nbsp;this&nbsp;new&nbsp;feature.&nbsp;Apache&nbsp;has&nbsp;announced&nbsp;support&nbsp;for&nbsp;the&nbsp;new&nbsp;<BR>
feature&nbsp;and&nbsp;will&nbsp;include&nbsp;it&nbsp;in&nbsp;the&nbsp;next&nbsp;Linux&nbsp;minor&nbsp;version.&nbsp;<BR>
Previously&nbsp;not&nbsp;optimally&nbsp;supported&nbsp;processors&nbsp;like&nbsp;the&nbsp;newer&nbsp;AMD&nbsp;and&nbsp;Cyrix&nbsp;<BR>
models&nbsp;are&nbsp;not&nbsp;up&nbsp;to&nbsp;par&nbsp;with&nbsp;Intel&nbsp;feature&nbsp;support.&nbsp;<BR>
The&nbsp;Linux&nbsp;ext2&nbsp;file&nbsp;system&nbsp;is&nbsp;one&nbsp;of&nbsp;its&nbsp;weaknesses.&nbsp;It&nbsp;is&nbsp;neither&nbsp;very&nbsp;<BR>
fast&nbsp;nor&nbsp;very&nbsp;secure&nbsp;(the&nbsp;file's&nbsp;metadata,&nbsp;its&nbsp;time&nbsp;stamps&nbsp;and&nbsp;privileges,&nbsp;<BR>
are&nbsp;not&nbsp;written&nbsp;synchronously&nbsp;with&nbsp;the&nbsp;file&nbsp;content's).&nbsp;There&nbsp;is&nbsp;some&nbsp;work&nbsp;<BR>
in&nbsp;progress&nbsp;to&nbsp;bring&nbsp;a&nbsp;server-strength&nbsp;file&nbsp;system&nbsp;to&nbsp;Linux.&nbsp;SGI&nbsp;is&nbsp;talking&nbsp;<BR>
of&nbsp;porting&nbsp;its&nbsp;excellent&nbsp;efs&nbsp;file&nbsp;system&nbsp;(which&nbsp;Linux&nbsp;2.4&nbsp;can&nbsp;now&nbsp;read)&nbsp;to&nbsp;<BR>
Linux&nbsp;and&nbsp;there&nbsp;are&nbsp;ports&nbsp;on&nbsp;the&nbsp;way&nbsp;for&nbsp;coda,&nbsp;a&nbsp;journaled&nbsp;file&nbsp;system.&nbsp;<BR>
Right&nbsp;now,&nbsp;on&nbsp;a&nbsp;big&nbsp;Linux&nbsp;server&nbsp;with&nbsp;40&nbsp;or&nbsp;50&nbsp;GBs&nbsp;of&nbsp;disks,&nbsp;it&nbsp;can&nbsp;take&nbsp;30&nbsp;<BR>
or&nbsp;40&nbsp;minutes&nbsp;after&nbsp;a&nbsp;power-failure&nbsp;to&nbsp;fsck&nbsp;(file&nbsp;system&nbsp;check)&nbsp;the&nbsp;whole&nbsp;<BR>
file&nbsp;system.&nbsp;With&nbsp;a&nbsp;journaled&nbsp;file&nbsp;system&nbsp;it&nbsp;would&nbsp;only&nbsp;take&nbsp;two&nbsp;or&nbsp;three&nbsp;<BR>
seconds.&nbsp;<BR>
One&nbsp;change&nbsp;introduced&nbsp;by&nbsp;2.4&nbsp;is&nbsp;a&nbsp;unified&nbsp;file-system&nbsp;buffer&nbsp;forread/write.&nbsp;<BR>
This&nbsp;will&nbsp;allow&nbsp;for&nbsp;less&nbsp;memory&nbsp;consumption&nbsp;and&nbsp;speed&nbsp;up&nbsp;I/O&nbsp;operation&nbsp;<BR>
somewhat.&nbsp;Also,&nbsp;the&nbsp;file&nbsp;system&nbsp;code&nbsp;within&nbsp;the&nbsp;kernel&nbsp;has&nbsp;been&nbsp;properly&nbsp;<BR>
adapted&nbsp;for&nbsp;better&nbsp;performance&nbsp;in&nbsp;SMB&nbsp;environments&nbsp;of&nbsp;up&nbsp;to&nbsp;8&nbsp;processors.&nbsp;<BR>
Many&nbsp;more&nbsp;critical-code&nbsp;sections&nbsp;have&nbsp;been&nbsp;put&nbsp;within&nbsp;locking&nbsp;brackets&nbsp;and&nbsp;<BR>
the&nbsp;lock&nbsp;areas&nbsp;are&nbsp;now&nbsp;much&nbsp;more&nbsp;granular.&nbsp;This&nbsp;will&nbsp;solve&nbsp;contention&nbsp;<BR>
problems&nbsp;and&nbsp;therefore&nbsp;increase&nbsp;system&nbsp;throughput.&nbsp;<BR>
OS/2&nbsp;partitions&nbsp;(OS/2&nbsp;is&nbsp;still&nbsp;alive&nbsp;and&nbsp;well)&nbsp;can&nbsp;now&nbsp;be&nbsp;read&nbsp;and&nbsp;written.&nbsp;<BR>
New&nbsp;Support&nbsp;for&nbsp;Busses,&nbsp;Devices,&nbsp;and&nbsp;Controllers&nbsp;This&nbsp;is&nbsp;where&nbsp;the&nbsp;new&nbsp;<BR>
version&nbsp;really&nbsp;shines,&nbsp;support&nbsp;for&nbsp;new&nbsp;buses,&nbsp;devices,&nbsp;and&nbsp;controllers.&nbsp;The&nbsp;<BR>
big&nbsp;news:&nbsp;There&nbsp;is&nbsp;now&nbsp;finally&nbsp;support&nbsp;for&nbsp;USB.&nbsp;On&nbsp;my&nbsp;machine,&nbsp;it&nbsp;worked&nbsp;<BR>
more&nbsp;or&nbsp;less&nbsp;flawlessly.&nbsp;In&nbsp;general&nbsp;it&nbsp;works&nbsp;better&nbsp;for&nbsp;low-bandwidth&nbsp;<BR>
devices&nbsp;such&nbsp;as&nbsp;mice&nbsp;and&nbsp;keyboards.&nbsp;Not&nbsp;well&nbsp;or&nbsp;not&nbsp;all&nbsp;supported&nbsp;on&nbsp;my&nbsp;<BR>
system&nbsp;were&nbsp;the&nbsp;USB&nbsp;modem&nbsp;and&nbsp;the&nbsp;USB&nbsp;printer&nbsp;connection.&nbsp;<BR>
The&nbsp;parallel-port&nbsp;driver&nbsp;has&nbsp;now&nbsp;been&nbsp;generalized.&nbsp;This&nbsp;lets&nbsp;a&nbsp;program&nbsp;read&nbsp;<BR>
and&nbsp;write&nbsp;the&nbsp;parallel&nbsp;port&nbsp;as&nbsp;with&nbsp;any&nbsp;other&nbsp;device.&nbsp;One&nbsp;positive&nbsp;<BR>
side-effect&nbsp;of&nbsp;this&nbsp;is&nbsp;that&nbsp;you&nbsp;can&nbsp;now&nbsp;have&nbsp;the&nbsp;console&nbsp;at&nbsp;boot&nbsp;go&nbsp;to&nbsp;the&nbsp;<BR>
parallel&nbsp;port,&nbsp;which&nbsp;gives&nbsp;you&nbsp;the&nbsp;possibility&nbsp;to&nbsp;print&nbsp;all&nbsp;boot&nbsp;messages&nbsp;<BR>
on&nbsp;paper.&nbsp;Access&nbsp;to&nbsp;the&nbsp;parallel&nbsp;port&nbsp;is&nbsp;now&nbsp;in&nbsp;DMA,&nbsp;which&nbsp;makes&nbsp;this&nbsp;<BR>
considerably&nbsp;faster.&nbsp;<BR>
There&nbsp;is&nbsp;now&nbsp;support&nbsp;for&nbsp;8&nbsp;IDE&nbsp;controllers&nbsp;from&nbsp;previously&nbsp;4.&nbsp;Linux&nbsp;will&nbsp;<BR>
correctly&nbsp;recognize&nbsp;and&nbsp;configure&nbsp;almost&nbsp;all&nbsp;IDE&nbsp;controllers&nbsp;in&nbsp;the&nbsp;PC&nbsp;<BR>
market&nbsp;now.&nbsp;This&nbsp;means&nbsp;that&nbsp;you&nbsp;should&nbsp;not&nbsp;experience&nbsp;a&nbsp;situation&nbsp;where&nbsp;the&nbsp;<BR>
install&nbsp;from&nbsp;CD&nbsp;is&nbsp;not&nbsp;possible&nbsp;because&nbsp;the&nbsp;CD-ROM&nbsp;drive&nbsp;is&nbsp;not&nbsp;recognized&nbsp;<BR>
before&nbsp;you&nbsp;installed&nbsp;a&nbsp;Linux&nbsp;that&nbsp;permits&nbsp;you&nbsp;to&nbsp;adapt&nbsp;the&nbsp;kernel;&nbsp;the&nbsp;<BR>
classic&nbsp;chicken&nbsp;and&nbsp;egg&nbsp;problem.&nbsp;<BR>
On&nbsp;one&nbsp;old&nbsp;HP&nbsp;laptop&nbsp;where&nbsp;I&nbsp;could&nbsp;previously&nbsp;not&nbsp;install&nbsp;my&nbsp;self-rolled&nbsp;<BR>
Linux&nbsp;2.2.5&nbsp;kernel&nbsp;with&nbsp;the&nbsp;RH&nbsp;installer,&nbsp;it&nbsp;now&nbsp;worked&nbsp;flawlessly&nbsp;on&nbsp;the&nbsp;<BR>
first&nbsp;try.&nbsp;This&nbsp;feature&nbsp;will&nbsp;speed&nbsp;up&nbsp;Linux&nbsp;acceptance&nbsp;more&nbsp;than&nbsp;all&nbsp;others&nbsp;<BR>
presented&nbsp;in&nbsp;this&nbsp;article.&nbsp;<BR>
The&nbsp;new&nbsp;kernels&nbsp;will&nbsp;significantly&nbsp;improve&nbsp;support&nbsp;for&nbsp;PC&nbsp;hardware.&nbsp;It&nbsp;will&nbsp;<BR>
become&nbsp;even&nbsp;easier&nbsp;for&nbsp;Windows&nbsp;users&nbsp;to&nbsp;switch&nbsp;over&nbsp;to&nbsp;Linux.&nbsp;For&nbsp;existing&nbsp;<BR>
Linux&nbsp;believers,&nbsp;unless&nbsp;you&nbsp;desperately&nbsp;need&nbsp;some&nbsp;of&nbsp;the&nbsp;new&nbsp;features&nbsp;<BR>
introduced&nbsp;with&nbsp;2.4&nbsp;you&nbsp;won't&nbsp;have&nbsp;to&nbsp;rush&nbsp;to&nbsp;get&nbsp;it.&nbsp;I&nbsp;have&nbsp;been&nbsp;running&nbsp;<BR>
2.3.11&nbsp;and&nbsp;2.3.10&nbsp;for&nbsp;some&nbsp;time&nbsp;now.&nbsp;Although&nbsp;these&nbsp;are&nbsp;development&nbsp;kernels&nbsp;<BR>
I&nbsp;never&nbsp;experienced&nbsp;any&nbsp;real&nbsp;stability&nbsp;problems&nbsp;with&nbsp;them.&nbsp;Linux&nbsp;was,&nbsp;is,&nbsp;<BR>
and&nbsp;will,&nbsp;hopefully,&nbsp;always&nbsp;be&nbsp;rock&nbsp;solid.&nbsp;<BR>
Linux&nbsp;cognoscenti&nbsp;expect&nbsp;RedHat&nbsp;to&nbsp;introduce&nbsp;the&nbsp;new&nbsp;2.4&nbsp;kernels&nbsp;with&nbsp;its&nbsp;<BR>
RH6.1&nbsp;or&nbsp;6.2&nbsp;release.&nbsp;It&nbsp;is&nbsp;probably&nbsp;advisable&nbsp;to&nbsp;wait&nbsp;for&nbsp;the&nbsp;major&nbsp;<BR>
distributions&nbsp;to&nbsp;come&nbsp;out&nbsp;instead&nbsp;of&nbsp;upgrading&nbsp;now.&nbsp;<BR>
Moshe&nbsp;Bar&nbsp;is&nbsp;an&nbsp;Israeli&nbsp;system&nbsp;administrator&nbsp;and&nbsp;OS&nbsp;researcher,&nbsp;who&nbsp;started&nbsp;<BR>
learning&nbsp;UNIX&nbsp;on&nbsp;a&nbsp;PDP-11&nbsp;with&nbsp;AT&amp;T&nbsp;Unix&nbsp;Release&nbsp;6&nbsp;back&nbsp;in&nbsp;1981.&nbsp;He&nbsp;holds&nbsp;<BR>
an&nbsp;M.Sc&nbsp;in&nbsp;computer&nbsp;science.&nbsp;Visit&nbsp;Moshe's&nbsp;website&nbsp;at&nbsp;<BR>
<A HREF="http://cvs.sentience.org/.">http://cvs.sentience.org/.</A>&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;www.cmpnet.com&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The&nbsp;Technology&nbsp;Network&nbsp;<BR>
Copyright&nbsp;1998&nbsp;CMP&nbsp;Media&nbsp;Inc.&nbsp;<BR>
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--&nbsp;<BR>
※&nbsp;来源:·BBS&nbsp;水木清华站&nbsp;bbs.net.tsinghua.edu.cn·[FROM:&nbsp;162.105.17.237]&nbsp;<BR>


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