On 12/23/2010 05:49 AM, Paolo Bonzini wrote: > On 12/22/2010 11:27 PM, Eric Blake wrote: >> https://bugzilla.redhat.com/show_bug.cgi?id=620363 >> >> When using -incoming stdio or -incoming exec:cat, qemu keeps the >> stdin fd open long after the migration is complete. Not to >> mention that exec:cat is horribly inefficient, by doubling the >> I/O and going through a popen interface in qemu. >> >> The new -incoming fd: of qemu 0.12.0 closes the fd after using >> it, and allows us to bypass an intermediary cat process for >> less I/O. >> >> It would also be possible to fix this bug for qemu< 0.12.0, by >> creating a dummy 'cat' process that reads from real fd and writes to a >> pipe, and pass the other end of the pipe into -incoming exec:cat or >> -incoming stdio, at the expense of even more I/O. I don't know if >> that is worth the patch, though. > > Since you are at it, you may also want to replace the usage of netcat > and Unix sockets with "-incoming fd:" and a one-way pipe. Not sure it's worth it. Is unix:path any less efficient than creating a one-way pipe for use by fd:n? Also, we can't replace netcat; the use of '-incoming "exec:nc -lU path"' is only used in libvirt that predates '-incoming unix:path', which also happens to predate '-incoming fd:n'. -- Eric Blake eblake@xxxxxxxxxx +1-801-349-2682 Libvirt virtualization library http://libvirt.org
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