From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [PATCH v6] vhost: allow for many vhost user ports
Date: Wed, 21 Dec 2016 10:06:36 -0800
Message-ID: <20161221100636.71a27b22@xeon-e3>
References: <1481729401-27546-1-git-send-email-jan.wickbom@ericsson.com>
 <1482313513-1709-1-git-send-email-yuanhan.liu@linux.intel.com>
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Cc: dev@dpdk.org, Patrik Andersson <patrik.r.andersson@ericsson.com>, Jan
 Wickbom <jan.wickbom@ericsson.com>
To: Yuanhan Liu <yuanhan.liu@linux.intel.com>
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On Wed, 21 Dec 2016 17:45:13 +0800
Yuanhan Liu <yuanhan.liu@linux.intel.com> wrote:

> From: Jan Wickbom <jan.wickbom@ericsson.com>
> 
> Currently select() is used to monitor file descriptors for vhostuser
> ports. This limits the number of ports possible to create since the
> fd number is used as index in the fd_set and we have seen fds > 1023.
> This patch changes select() to poll(). This way we can keep an
> packed (pollfd) array for the fds, e.g. as many fds as the size of
> the array.
> 
> Also see:
> http://dpdk.org/ml/archives/dev/2016-April/037024.html
> 
> Reported-by: Patrik Andersson <patrik.r.andersson@ericsson.com>
> Signed-off-by: Jan Wickbom <jan.wickbom@ericsson.com>
> Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>

Why not epoll()? It scales much better. The old System V poll
is just as bad with 1023 fd's.