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<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>LKML: Arnd Bergmann: Re: [PATCH 00/05] robust per_cpu allocation for modules</title><link href="/css/message.css" rel="stylesheet" type="text/css" /><link href="/css/wrap.css" rel="alternate stylesheet" type="text/css" title="wrap" /><link href="/css/nowrap.css" rel="stylesheet" type="text/css" title="nowrap" /><link href="/favicon.ico" rel="shortcut icon" /><script src="/js/simple-calendar.js" type="text/javascript"></script><script src="/js/styleswitcher.js" type="text/javascript"></script><link rel="alternate" type="application/rss+xml" title="lkml.org : last 100 messages" href="/rss.php" /><link rel="alternate" type="application/rss+xml" title="lkml.org : last messages by Arnd Bergmann" href="/groupie.php?aid=22227" /><script> var _paq = window._paq = window._paq || []; /* tracker methods like "setCustomDimension" should be called before "trackPageView" */ _paq.push(["setDoNotTrack", true]); _paq.push(["disableCookies"]); _paq.push(['trackPageView']); _paq.push(['enableLinkTracking']); (function() { var u="//m.lkml.org/"; _paq.push(['setTrackerUrl', u+'matomo.php']); _paq.push(['setSiteId', '1']); var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0]; g.async=true; g.src=u+'matomo.js'; s.parentNode.insertBefore(g,s); })(); </script></head><body onload="es.jasper.simpleCalendar.init();" itemscope="itemscope" itemtype="http://schema.org/BlogPosting"><table border="0" cellpadding="0" cellspacing="0"><tr><td width="180" align="center"><a href="/"><img style="border:0;width:135px;height:32px" src="/images/toprowlk.gif" alt="lkml.org" /></a></td><td width="32">聽</td><td class="nb"><div><a class="nb" href="/lkml"> [lkml]</a> 聽 <a class="nb" href="/lkml/2006"> [2006]</a> 聽 <a class="nb" href="/lkml/2006/4"> [Apr]</a> 聽 <a class="nb" href="/lkml/2006/4/16"> [16]</a> 聽 <a class="nb" href="/lkml/last100"> [last100]</a> 聽 <a href="/rss.php"><img src="/images/rss-or.gif" border="0" alt="RSS Feed" /></a></div><div>Views: <a href="#" class="nowrap" onclick="setActiveStyleSheet('wrap');return false;">[wrap]</a><a href="#" class="wrap" onclick="setActiveStyleSheet('nowrap');return false;">[no wrap]</a> 聽 <a class="nb" href="/lkml/mheaders/2006/4/16/58" onclick="this.href='/lkml/headers'+'/2006/4/16/58';">[headers]</a>聽 <a href="/lkml/bounce/2006/4/16/58">[forward]</a>聽 </div></td><td width="32">聽</td></tr><tr><td valign="top"><div class="es-jasper-simpleCalendar" baseurl="/lkml/"></div><div class="threadlist">Messages in this thread</div><ul class="threadlist"><li class="root"><a href="/lkml/2006/4/14/137">First message in thread</a></li><li><a href="/lkml/2006/4/16/25">Arnd Bergmann</a><ul><li><a href="/lkml/2006/4/16/33">"Tony Luck"</a></li><li><a href="/lkml/2006/4/16/49">Steven Rostedt</a><ul><li class="origin"><a href="/lkml/2006/4/16/60">Arnd Bergmann</a><ul><li><a href="/lkml/2006/4/16/60">Steven Rostedt</a></li></ul></li></ul></li><li><a href="/lkml/2006/4/17/93">Ravikiran G Thirumalai</a></li></ul></li></ul></td><td width="32" rowspan="2" class="c" valign="top"><img src="/images/icornerl.gif" width="32" height="32" alt="/" /></td><td class="c" rowspan="2" valign="top" style="padding-top: 1em"><table><tr><td><table><tr><td class="lp">From</td><td class="rp" itemprop="author">Arnd Bergmann <></td></tr><tr><td class="lp">Subject</td><td class="rp" itemprop="name">Re: [PATCH 00/05] robust per_cpu allocation for modules</td></tr><tr><td class="lp">Date</td><td class="rp" itemprop="datePublished">Mon, 17 Apr 2006 04:07:23 +0200</td></tr></table></td><td></td></tr></table><pre itemprop="articleBody">Am Monday 17 April 2006 02:45 schrieb Steven Rostedt:<br />> > - does not work in real mode, so percpu data can't be used<br />> > 聽 inside exception handlers on some architectures.<br />><br />> This is probably a big issue. 聽I believe interrupt context in hrtimers<br />> uses per_cpu variables.<br /><br />If it's just about hrtimers, it should be harmless, since they<br />are run in softirq context. Even regular interrupt handlers are<br />always called with paging enabled, otherwise you could not<br />have them im modules.<br /><br />> > - memory consumption is rather high when PAGE_SIZE is large<br />><br />> That's also something that I'm trying to solve. 聽To use the least amount<br />> of memory and still have the performance.<br />><br />> Now, I've also thought about allocating per_cpu and when a module is<br />> loaded, reallocate more memory and copy it again. 聽Use something like<br />> the kstopmachine to sync the system so that the CPUS don't update any<br />> per_cpu variables while this is happening, so that things can't get out<br />> of sync.<br /><br />I guess this breaks if someone holds a pointer to a per-cpu variable<br />while a module gets loaded.<br /><br /> Arnd <><<br />-<br />To unsubscribe from this list: send the line "unsubscribe linux-kernel" in<br />the body of a message to majordomo@vger.kernel.org<br />More majordomo info at <a href="http://vger.kernel.org/majordomo-info.html">http://vger.kernel.org/majordomo-info.html</a><br />Please read the FAQ at <a href="http://www.tux.org/lkml/">http://www.tux.org/lkml/</a><br /><br /></pre></td><td width="32" rowspan="2" class="c" valign="top"><img src="/images/icornerr.gif" width="32" height="32" alt="\" /></td></tr><tr><td align="right" valign="bottom"> 聽 </td></tr><tr><td align="right" valign="bottom">聽</td><td class="c" valign="bottom" style="padding-bottom: 0px"><img src="/images/bcornerl.gif" width="32" height="32" alt="\" /></td><td class="c">聽</td><td class="c" valign="bottom" style="padding-bottom: 0px"><img src="/images/bcornerr.gif" width="32" height="32" alt="/" /></td></tr><tr><td align="right" valign="top" colspan="2"> 聽 </td><td class="lm">Last update: 2006-04-17 04:09 聽聽 [from the cache]<br />漏2003-2020 <a href="http://blog.jasper.es/"><span itemprop="editor">Jasper Spaans</span></a>|hosted at <a href="https://www.digitalocean.com/?refcode=9a8e99d24cf9">Digital Ocean</a> and my Meterkast|<a href="http://blog.jasper.es/categories.html#lkml-ref">Read the blog</a></td><td>聽</td></tr></table><script language="javascript" src="/js/styleswitcher.js" type="text/javascript"></script></body></html>