Messages in this thread | | | Date | Tue, 20 Apr 2004 14:41:18 +0200 | From | "Prakash K. Cheemplavam" <> | Subject | Re: poor sata performance on 2.6 |
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Jeff Garzik wrote: > Denis Vlasenko wrote: > >> On Thursday 15 April 2004 17:48, Konstantin Sobolev wrote: >> >>> On Thursday 15 April 2004 18:33, Justin Cormack wrote: >>> >>>> On Thu, 2004-04-15 at 15:26, Konstantin Sobolev wrote: >>>> >>>>> On Thursday 15 April 2004 18:00, Justin Cormack wrote: >>>>> >>>>>> hmm, odd. I get 50MB/s or so from normal (7200, 8MB cache) WD disks, >>>>>> and Seagate from the same controller. Can you send lspci, >>>>>> /proc/interrupts and dmesg... >>>>> >>>>> >>>>> Attached are files for 2.6.5-mm5 with highmem, ACPI and APIC turned >>>>> off. >>>> >>>> >>>> ah. Make a filesystem on it and mount it and try again. I see you have >>>> no partition table and so probably no filesystem. This means the block >>>> size is set to default 512byte not 4k which makes disk operations slow. >>>> Any filesystem should default to block size of 4k, eg ext2. >>> [snip] >>> So first time it gave the same loosy 27 MB/s and subsequent tests give >>> pretty good 68 MB/s! Why? >> >> >> >> Time to CC ide/libata/block layer folks >> >> Jeff Garzik <jgarzik@pobox.com> >> libata man > > > > It seems like the situation is already resolved, to me. > > When you mount a filesystem, it changes the default block size (512 or > 1024) to the filesystem block size, normally 4096. This would certainly > increase the throughput.
Hi Jeff,
it is NOT resolved: I just tried libata again, and I can observe the same behaviour: I just did a "cat /dev/sda >/dev/null" and watched gkrellm2 showing the throughoutput. The first tiem I do the cat I only got about 27mb/s, no matter how ong I waited, but all subsequent cat gave me about >60mb/s. So there is a tiny bug in libata, I guess, as when using the siimage.c ide driver, already the first cat gives me maximum throughoutput. I am using 2.6.5-mm4 based kernel. Filesystems were mounted/ I didn't change anything between first and secound cat.
bye,
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