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Compress pending socket buffer data once it is marked ready.

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Apply similar logic from sbcompress to pending data in the socket
buffer once it is marked ready via sbready.  Normally sbcompress
merges small mbufs to reduce the length of mbuf chains in the socket
buffer.  However, sbcompress cannot do this for mbufs marked
M_NOTREADY.  sbcompress_ready is now called from sbready when mbufs
are marked ready to merge small mbuf chains once the data is available
to copy.

Submitted by:	gallatin (earlier version)
Reviewed by:	gallatin, hselasky, rrs
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D20616
This commit is contained in:
John Baldwin 2019-06-29 00:50:25 +00:00
parent cec06a3edc
commit 3807631b8e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=349531
1 changed files with 74 additions and 0 deletions
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74
sys/kern/uipc_sockbuf.c
View file

@ -88,6 +88,78 @@ sbm_clrprotoflags(struct mbuf *m, int flags)
}
}
/*
* Compress M_NOTREADY mbufs after they have been readied by sbready().
*
* sbcompress() skips M_NOTREADY mbufs since the data is not available to
* be copied at the time of sbcompress(). This function combines small
* mbufs similar to sbcompress() once mbufs are ready. 'm0' is the first
* mbuf sbready() marked ready, and 'end' is the first mbuf still not
* ready.
*/
static void
sbready_compress(struct sockbuf *sb, struct mbuf *m0, struct mbuf *end)
{
struct mbuf *m, *n;
int ext_size;
SOCKBUF_LOCK_ASSERT(sb);
if ((sb->sb_flags & SB_NOCOALESCE) != 0)
return;
for (m = m0; m != end; m = m->m_next) {
MPASS((m->m_flags & M_NOTREADY) == 0);
/* Compress small unmapped mbufs into plain mbufs. */
if ((m->m_flags & M_NOMAP) && m->m_len <= MLEN) {
MPASS(m->m_flags & M_EXT);
ext_size = m->m_ext.ext_size;
if (mb_unmapped_compress(m) == 0) {
sb->sb_mbcnt -= ext_size;
sb->sb_ccnt -= 1;
}
}
/*
* NB: In sbcompress(), 'n' is the last mbuf in the
* socket buffer and 'm' is the new mbuf being copied
* into the trailing space of 'n'. Here, the roles
* are reversed and 'n' is the next mbuf after 'm'
* that is being copied into the trailing space of
* 'm'.
*/
n = m->m_next;
while ((n != NULL) && (n != end) && (m->m_flags & M_EOR) == 0 &&
M_WRITABLE(m) &&
(m->m_flags & M_NOMAP) == 0 &&
n->m_len <= MCLBYTES / 4 && /* XXX: Don't copy too much */
n->m_len <= M_TRAILINGSPACE(m) &&
m->m_type == n->m_type) {
KASSERT(sb->sb_lastrecord != n,
("%s: merging start of record (%p) into previous mbuf (%p)",
__func__, n, m));
m_copydata(n, 0, n->m_len, mtodo(m, m->m_len));
m->m_len += n->m_len;
m->m_next = n->m_next;
m->m_flags |= n->m_flags & M_EOR;
if (sb->sb_mbtail == n)
sb->sb_mbtail = m;
sb->sb_mbcnt -= MSIZE;
sb->sb_mcnt -= 1;
if (n->m_flags & M_EXT) {
sb->sb_mbcnt -= n->m_ext.ext_size;
sb->sb_ccnt -= 1;
}
m_free(n);
n = m->m_next;
}
}
SBLASTRECORDCHK(sb);
SBLASTMBUFCHK(sb);
}
/*
* Mark ready "count" units of I/O starting with "m". Most mbufs
* count as a single unit of I/O except for EXT_PGS-backed mbufs which
@ -138,6 +210,7 @@ sbready(struct sockbuf *sb, struct mbuf *m0, int count)
}
if (!blocker) {
sbready_compress(sb, m0, m);
return (EINPROGRESS);
}
@ -150,6 +223,7 @@ sbready(struct sockbuf *sb, struct mbuf *m0, int count)
}
sb->sb_fnrdy = m;
sbready_compress(sb, m0, m);
return (0);
}