Re: [RESEND] tuning linux for high network performance?

From: Roy Sigurd Karlsbakk (roy@karlsbakk.net)
Date: Wed Oct 23 2002 - 08:36:24 EST

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> >
> > 905182 total 0.4741
> > 121426 csum_partial_copy_generic 474.3203
>
> Well, maybe take a look at this func and try to optimize it?

I don't know assembly that good - sorry.

> > 93633 default_idle 1800.6346
> > 74665 do_wp_page 111.1086
>
> What's this?

do_wp_page is Defined as a function in: mm/memory.c

comments from the file:

/*
* This routine handles present pages, when users try to write
* to a shared page. It is done by copying the page to a new address
* and decrementing the shared-page counter for the old page.
*
* Goto-purists beware: the only reason for goto's here is that it results
* in better assembly code.. The "default" path will see no jumps at all.
*
* Note that this routine assumes that the protection checks have been
* done by the caller (the low-level page fault routine in most cases).
* Thus we can safely just mark it writable once we've done any necessary
* COW.
*
* We also mark the page dirty at this point even though the page will
* change only once the write actually happens. This avoids a few races,
* and potentially makes it more efficient.
*
* We hold the mm semaphore and the page_table_lock on entry and exit
* with the page_table_lock released.
*/

>
> > 65857 ide_intr 184.9916
>
> You have 1 ide_intr per 2 csum_partial_copy_generic... hmmm...
> how large is your readahead? I assume you'd like to fetch
> more sectors from ide per interrupt. (I hope you do DMA ;)

doing DMA - RAID-0 with 1MB chunk size on 4 disks.

> > 53636 handle_IRQ_event 432.5484
> > 21973 do_softirq 107.7108
> > 20498 e1000_intr 244.0238
>
> I know zero about networking, but why 120 000 csum_partial_copy_generic
> and inly 20 000 nic interrupts? That may be abnormal.

sorry
I don't know

-- Roy Sigurd Karlsbakk, Datavaktmester ProntoTV AS - http://www.pronto.tv/ Tel: +47 9801 3356

Computers are like air conditioners. They stop working when you open Windows.

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