Tom Haapanen wrote:
I have been using FreeBSD (and other forms of *BSD) a long time, but I'm new
to the world of jails. I have been doing reading on them, but there is one
question I have not been able to find an answer to, and that's the
efficiency of memory usage when using multiple jails on a single system.
With "conventional" virtual machines (VMware, Virtual Server et al),
essentially each VM is opaque to the host OS, and thus has to be allocated X
MB of memory, which that VM then manages internally.
im been expermenting with some of this
disk cache (malloc, etc) is shared.
if httpd is different in each jail (even if its the same), then
example:
jail 1 has 4 httpd's running, one copy (of binary) will be in memory, 4
copies of data structure
jail 2 has 10 httpd's running, its got one (more) copy of binary, and 10
copies of data structure.
HOWEVER if you nullmount /usr/local/bin ../sbin .../libexec ../lib then
you CAN share the one httpd binary.
other issue is static libs.
in /usr/lib
these aren't likely shares, as when you build the jail, you made COPIES
of /usr/lib
so, nullfs mount /usr/lib /usr/bin /usr/sbin /sbin, /usr/libexec, maybe
you can get the most out of it.
(but, 6 freebsd jails use a heck of a lot ram than 6 vmware images)
However, since jails are based on the FreeBSD kernel, and both host and
guest OSs are identical, I am wondering whether there are any comparative
efficiencies in memory utilization. Will the jails share the disk cache,
for example, or does each jail allocate its own? Will other kernel
structures (and code!) be shared across jails, or allocated multiple times?
And what about userland applications, like httpd, for example? (I suspect
userland would not be able to benefit, but that's just a guess.)
Thanks for any insight into this ...
Tom
_______________________________________________
[email protected] mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-jail
To unsubscribe, send any mail to "[email protected]"
--
Michael Scheidell, CTO
Phone: 561-999-5000, x 1259
> *| *SECNAP Network Security Corporation
* Certified SNORT Integrator
* 2008-9 Hot Company Award Winner, World Executive Alliance
* Five-Star Partner Program 2009, VARBusiness
* Best Anti-Spam Product 2008, Network Products Guide
* King of Spam Filters, SC Magazine 2008
_________________________________________________________________________
This email has been scanned and certified safe by SpammerTrap(r).
For Information please see http://www.secnap.com/products/spammertrap/
_________________________________________________________________________
_______________________________________________
[email protected] mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-jail
To unsubscribe, send any mail to "[email protected]"
