{"id":66,"date":"2008-01-25T19:27:14","date_gmt":"2008-01-26T03:27:14","guid":{"rendered":"http:\/\/intr.overt.org\/blog\/?p=66"},"modified":"2008-01-25T19:27:14","modified_gmt":"2008-01-26T03:27:14","slug":"slow-memory-card-performance-on-n800-with-os2008","status":"publish","type":"post","link":"https:\/\/blog.intr.overt.org\/?p=66","title":{"rendered":"Slow memory card performance on N800 with OS2008"},"content":{"rendered":"<p>After I released my latest kernel with 48MHz support for accessing MMC and SD cards, a couple of readers noticed that the card performance was surprisingly low (around 4MB\/s) which was way slower than I saw when I did testing way back when. Lucky, I kept those old results around and the fastest card I have was reporting 12.9MB\/s and it too is now doing 4.something. That&#8217;s not good. The really weird part is that the transfer rate seems to *increase* when I put load on the CPU! Obviously, there&#8217;s a dimishing returns behaviour here but certainly if I put ~20% load on the CPU, I see the transfer rate increase by about 50%.<\/p>\n<p>So, given that, it seems like there&#8217;s something funky going on with the cpu power conservation and it&#8217;s not speeding up when it needs to to maximise the data transfers.<\/p>\n<p>I&#8217;ve filed <a href=\"https:\/\/bugs.maemo.org\/show_bug.cgi?id=2838\">bug 2838<\/a> for this problem.<\/p>\n<p>In the meantime, my 48MHz patch is rather accademic as you&#8217;re never going to reach the hardware limits.<\/p>\n<p>My n810 is now in the mail and I&#8217;ll report if I see any difference in behaviour.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>After I released my latest kernel with 48MHz support for accessing MMC and SD cards, a couple of readers noticed that the card performance was surprisingly low (around 4MB\/s) which was way slower than I saw when I did testing way back when. Lucky, I kept those old results around and the fastest card I [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,6],"tags":[],"class_list":["post-66","post","type-post","status-publish","format-standard","hentry","category-maemo","category-sdmmc"],"_links":{"self":[{"href":"https:\/\/blog.intr.overt.org\/index.php?rest_route=\/wp\/v2\/posts\/66"}],"collection":[{"href":"https:\/\/blog.intr.overt.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.intr.overt.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.intr.overt.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.intr.overt.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=66"}],"version-history":[{"count":0,"href":"https:\/\/blog.intr.overt.org\/index.php?rest_route=\/wp\/v2\/posts\/66\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.intr.overt.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=66"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.intr.overt.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=66"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.intr.overt.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=66"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}