Date: Fri, 6 Sep 2013 12:10:47 -0700 From: hiren panchasara <hiren.panchasara@gmail.com> To: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Subject: mbuf autotuning changes Message-ID: <CALCpEUFxaXKh4%2B8evratZYE3JyfyTmrL7rzpBqUJ%2B_S3Ff-AcA@mail.gmail.com>
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tunable_mbinit() in kern_mbuf.c looks like this:
119 /*
120 * The default limit for all mbuf related memory is 1/2 of all
121 * available kernel memory (physical or kmem).
122 * At most it can be 3/4 of available kernel memory.
123 */
124 realmem = qmin((quad_t)physmem * PAGE_SIZE,
125 vm_map_max(kmem_map) - vm_map_min(kmem_map));
126 maxmbufmem = realmem / 2;
127 TUNABLE_QUAD_FETCH("kern.ipc.maxmbufmem", &maxmbufmem);
128 if (maxmbufmem > realmem / 4 * 3)
129 maxmbufmem = realmem / 4 * 3;
If I am reading the code correctly, we loose the value on line 126 when we
do FETCH on line 127.
And after line 127, if we havent specified kern.ipc.maxmbufmem (in
loader.conf - I guess...), we set that value to 0.
And because of that the if condition on line 128 is almost always false?
What am I missing here?
Thanks,
Hiren
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