On Saturday 20 November 2010 13:26:03 David W Noon wrote: > On Sat, 20 Nov 2010 00:10:02 +0100, Mick wrote about Re: [gentoo-user]
> >Short of measuring the latency with some system (which I wouldn't know > >how) I have experimented with setting the /boot partition on primary > >and logical partitions and the difference (on a stopwatch) was > >measurable in seconds betweeen having said partition on a primary and > >having it on a logical. Furthermore, sda7 was slower than sda5. > > Unless you have the mother of all initrd's or initramfs's, you cannot > have /boot on a logical partition -- only a primary partition, as BIOS > interrupts will only access raw drives and primary partitions. If you do > put /boot on a logical partition, you will pay the "lookup" overhead > repeatedly as part of the early bootstrap process. Since you won't have > a kernel running at that time. no caching, including device mapping, > will be in force. It will be dog slow if /boot is not in the primary > partition table. Thanks David, this explains then why booting from a logical partition takes longer. After the GRUB code has run the OS loads normally, but that initial delay is explained by the lookup overhead (hence I thought that no much caching is happening at that stage). -- Regards, Mick
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