From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Theurer <habanero@us.ibm.com>
Subject: Re: More network tests with xenoprofile this time
Date: Tue, 21 Jun 2005 21:22:20 -0500
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To: "Santos, Jose Renato G" <joserenato.santos@hp.com>
Cc: Ian Pratt <m+Ian.Pratt@cl.cam.ac.uk>, xen-devel@lists.xensource.com, "Turner, Yoshio" <yoshio_turner@hp.com>, Aravind Menon <aravind.menon@epfl.ch>, G John Janakiraman <john@arivalai.hpl.hp.com>, William Cohen <wcohen@redhat.com>
List-Id: xen-devel@lists.xenproject.org

FWIW, I took a look at find_domain_by_id() and swapped out the rw lock 
with a spin lock for domlist_lock.  The time spent in the this function 
was reduced by 18%.  This function was certainly not the "hottest" one I 
recorded while running netperf, but every little bit helps I suppose.  
Below are before/after xenoprofile snippets:

before:

547036   6.32      xen-unstable-syms mask_and_ack_level_ioapic_irq
510448   5.90      xen-unstable-syms end_level_ioapic_irq
463386   5.35 vmlinux-2.6.11-xen0-up      net_tx_action
371072   4.29                 tg3.ko      tg3_interrupt
261341   3.02      xen-unstable-syms  find_domain_by_id
237601   2.75      xen-unstable-syms          hypercall
228649   2.64 vmlinux-2.6.11-xen0-up         nf_iterate
215634   2.49      xen-unstable-syms do_update_va_mapping
214077   2.47 vmlinux-2.6.11-xen0-up      net_rx_action

after:

549276   6.35      xen-unstable-syms mask_and_ack_level_ioapic_irq
511693   5.91      xen-unstable-syms end_level_ioapic_irq
466873   5.39 vmlinux-2.6.11-xen0-up      net_tx_action
375702   4.34                 tg3.ko      tg3_interrupt
239219   2.76      xen-unstable-syms          hypercall
230641   2.67 vmlinux-2.6.11-xen0-up         nf_iterate
220480   2.55      xen-unstable-syms do_update_va_mapping
217472   2.51                 tg3.ko             tg3_rx
217029   2.51 vmlinux-2.6.11-xen0-up      net_rx_action
214271   2.48      xen-unstable-syms  find_domain_by_id

Has anyone thought about using read-copy-update in Xen?

I plan on looking at the two irq functions next.

-Andrew