Na página Linux nfsd(8)
man :
SYNOPSIS
/usr/sbin/rpc.nfsd [options] nproc
...
nproc specify the number of NFS server threads. By default, eight threads are started. However, for optimum performance several threads should be used. The actual figure depends on the number of and the work load created by the NFS clients, but a useful starting point is eight threads. Effects of modifying that number can be checked using the nfsstat(8) program.
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CONFIGURATION FILE
Many of the options that can be set on the command line can also be controlled through values set in the [nfsd] section of the /etc/nfs.conf configuration file. Values recognized include: threads The number of threads to start. ...
Eu arriscaria a sua melhor opção é modificar /etc/nfs.conf
, assumindo que é assim que a instalação do Linux é configurada.