Date: Tue, 30 Mar 2004 18:58:28 +0200 From: des@des.no (Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?=) To: current@freebsd.org Subject: performance of jailed processes Message-ID: <xzpisgm46h7.fsf@dwp.des.no>
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Can anyone explain why jailed processes seem to perform much worse than non-jailed processes in recent -CURRENT? Specifically, running a query against a remote MySQL server from inside a jail takes an order of magnitude more time than from outside the jail. Tcpdump shows that the TCP packets carrying the result are evenly spaced, so this is not a matter of the server timing out on a DNS lookup or anything like that. Running a configure script also takes much longer inside the jail than outisde, and again, progress is even (though slow), so it is clearly not a matter of DNS timing out. There is no NFS or NIS in the equation either. Parts of the file space inside the jail is a nullfs mount, but we've also tried without nullfs. The system currently uses SCHED_ULE, but we had similar trouble with SCHED_4BSD on 5.1-RELEASE before we went -CURRENT. The machine currently has ~2600 processes running in ~400 jails. Is it conceivable that be scalability issues, perhaps in the credentials code, could cause vastly increased syscall overhead for jailed processes? DES --=20 Dag-Erling Sm=C3=B8rgrav - des@des.no
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