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> It commits your changes to the journal every five seconds. But your data > is then only in the journal. It still needs to be written into your files. > That writeback is controlled by the normal kernel 30-second writeback > timing. If that writeback isn't keeping up, kjournald needs to > force the writeback so it can recycle that data's space in the journal. > > While that writeback is happening, everything tends to wait on it. Doesn't bdflush let you control this? I noted in my first post that we'd played with changing bdflush params as described here: http://www-106.ibm.com/developerworks/linux/library/l-fs8.html?dwzone=linux And set them to this: [root@server5 hm]# cat /proc/sys/vm/bdflush 39 500 0 0 60 300 60 0 0 Shouldn't this reduce it to writing every 3 seconds? We tried lowering some of the values even further based on the description here: http://www.bb-zone.com/zope/bbzone/docs/slgfg/part2/cha04/sec04 So we altered the first one (nfract) to 10(%) to try and keep the dirty buffer list small, but that didn't help either. I sort of thought that age_buffer at 3 seconds would be more likely to activate anyway than 40% of buffers being dirty? > It is suspected that ext3 gets the flushtime on those buffers > wrong as well, so the writeback isn't happening right. So you're saying that ext3 is somehow breaking the standard kernel writeback code? Is this something they know about, and/or are addressing? Rob - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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