Re: cvs commit: squid/src/fs/aufs aiops.c async_io.c store_asyncufs.h

From: Serassio Guido <>
Date: Mon, 25 Apr 2005 23:36:02 +0200

Hi Henrik,

At 22.45 25/04/2005, Henrik Nordstrom wrote:

>On Mon, 25 Apr 2005 wrote:
>> - Usage of FD_READ_METHOD/FD_WRITE_METHOD instead of read()/write() int the
>> async-io completion event for better portability.
>Note: FD_READ/WRITE_METHOD relies upon the fd_table, which the async-io
>threads intentionally is/was kept from using. Not sure if it is a good
>thing to make the async-io threads dependent on the fd_table.

This is an interesting question.

On platforms where there is equivalence of Pipe, File and Socket Handles
and read()/write() can be used in place of recv()/send() its possible have
the async-io threads independent from the fd_table.
But when the equivalence is not available, things becomes more complex.
When using read() or write() is mandatory to use a function wrapper that
looks into fd_table for select the correct function call to use. This cause
a significative overhead.

Thinking again about this, could be a good solution save the function
pointer to FD_WRITE_METHOD/FD_READ_METHOD after the done pipe
initialization, and use this function pointer into threads code to call the
correct function call, without any other lookup into fd_table and without
significative overhead.



Guido Serassio
Acme Consulting S.r.l. - Microsoft Certified Partner
Via Lucia Savarino, 1 10098 - Rivoli (TO) - ITALY
Tel. : +39.011.9530135 Fax. : +39.011.9781115
Received on Mon Apr 25 2005 - 15:36:25 MDT

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