Date: Thu, 1 May 1997 17:08:23 -0500 (CDT) From: Mark Tinguely <tinguely@plains.nodak.edu> To: freebsd-atm@freebsd.org, freebsd-hackers@freebsd.org Subject: custom free for external mbuf Message-ID: <199705012208.RAA03104@plains.nodak.edu>
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back in October, I said that I wanted to add a permanent association
between an external mbuf and the external buffer. I call this M_PERM.
below is a context diff from 2.2.1-RELEASE. I have a card that holds
hundreds of mbufs until the ATM card gets data, then they will pass
through some networks stack and when released they get requeued to
the ATM card. I want to lower the cost of making/breaking the mbuf
to external connection, and besides since I hold so many mbufs in the
ATM queue, I do not want to have other devices fighting the card for
resources.
This is backward compatible with other external mbuf and should have
no impact with existing code.
The line:
m->m_next = (struct mbuf *) 0;
could be put in the ext_free() routine, I added it here to be consistant
with the rest of the macro.
As a side issue, I still have a concern with others drivers setting the
ext_free() routine without checking if there is already a ext_free() routine.
we hashed this a bit back in October, I refined my changes. I am sending this
to hackers for comments before submitting. If there strong objections to the
change, I will keep it only as a local change for the driver.
--mark.
---------- sys/sys/mbuf.h and /usr/include/sys/mbuf.h ------------
*** mbuf.h.orig Mon Aug 19 13:30:15 1996
--- mbuf.h Thu May 1 14:37:08 1997
***************
*** 123,128 ****
--- 123,129 ----
#define M_PKTHDR 0x0002 /* start of record */
#define M_EOR 0x0004 /* end of record */
#define M_PROTO1 0x0008 /* protocol-specific */
+ #define M_PERM 0x0010 /* permanently associated external storage */
/* mbuf pkthdr flags, also in m_flags */
#define M_BCAST 0x0100 /* send/received as link-level broadcast */
***************
*** 287,296 ****
} \
} \
(n) = (m)->m_next; \
! (m)->m_type = MT_FREE; \
! mbstat.m_mtypes[MT_FREE]++; \
! (m)->m_next = mmbfree; \
! mmbfree = (m); \
)
/*
--- 288,301 ----
} \
} \
(n) = (m)->m_next; \
! if ((m)->m_flags & M_PERM) \
! m->m_next = (struct mbuf *) 0; \
! else { \
! (m)->m_type = MT_FREE; \
! mbstat.m_mtypes[MT_FREE]++; \
! (m)->m_next = mmbfree; \
! mmbfree = (m); \
! } \
)
/*
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