Date: Fri, 8 Jan 2016 02:29:22 +0000 From: "sepherosa_gmail.com (Sepherosa Ziehau)" <phabric-noreply@FreeBSD.org> To: freebsd-net@freebsd.org Subject: [Differential] [Request, 6 lines] D4825: tcp/lro: Add network driver configurable LRO entry depth Message-ID: <differential-rev-PHID-DREV-ou2jiti5cx3pzqhm5pb2-req@FreeBSD.org>
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[-- Attachment #1 --] sepherosa_gmail.com created this revision. sepherosa_gmail.com added reviewers: network, adrian, delphij, decui_microsoft.com, honzhan_microsoft.com, howard0su_gmail.com, glebius. sepherosa_gmail.com added a subscriber: freebsd-net-list. Herald added a reviewer: transport. REVISION SUMMARY When there is only tiny amount of TCP connections and the host is slow, e.g. in VM, holding too much TCP segments in an LRO entry will cause RX performance degradation. We now allow network drivers to configure how deep one LRO entry should be. https://reviews.freebsd.org/D4824 has a disabled network driver usage example. Reviewed by: Hongjiang Zhang <honzhan microsoft com>, Dexuan Cui <decui microsoft com>, Jun Su <junsu microsoft com> Tested by: me (local), Hongjiang Zhang <honzhan microsoft com> (directly connected 40Ge) Sponsored by: Microsoft OSTC BTW, I think some drivers already put a limit on the # of drivers holding TCP segments, e.g. oce(4), though oce(4) does not use per-LRO entry depth. REVISION DETAIL https://reviews.freebsd.org/D4825 AFFECTED FILES sys/netinet/tcp_lro.c sys/netinet/tcp_lro.h CHANGE DETAILS diff --git a/sys/netinet/tcp_lro.h b/sys/netinet/tcp_lro.h --- a/sys/netinet/tcp_lro.h +++ b/sys/netinet/tcp_lro.h @@ -79,6 +79,7 @@ int lro_flushed; int lro_bad_csum; int lro_cnt; + int lro_hiwat; struct lro_head lro_active; struct lro_head lro_free; diff --git a/sys/netinet/tcp_lro.c b/sys/netinet/tcp_lro.c --- a/sys/netinet/tcp_lro.c +++ b/sys/netinet/tcp_lro.c @@ -77,6 +77,7 @@ lc->lro_queued = 0; lc->lro_flushed = 0; lc->lro_cnt = 0; + lc->lro_hiwat = 65535; SLIST_INIT(&lc->lro_free); SLIST_INIT(&lc->lro_active); @@ -501,7 +502,7 @@ } /* Flush now if appending will result in overflow. */ - if (le->p_len > (65535 - tcp_data_len)) { + if (le->p_len > (lc->lro_hiwat - tcp_data_len)) { SLIST_REMOVE(&lc->lro_active, le, lro_entry, next); tcp_lro_flush(lc, le); break; @@ -559,7 +560,7 @@ * If a possible next full length packet would cause an * overflow, pro-actively flush now. */ - if (le->p_len > (65535 - lc->ifp->if_mtu)) { + if (le->p_len > (lc->lro_hiwat - lc->ifp->if_mtu)) { SLIST_REMOVE(&lc->lro_active, le, lro_entry, next); tcp_lro_flush(lc, le); } else EMAIL PREFERENCES https://reviews.freebsd.org/settings/panel/emailpreferences/ To: sepherosa_gmail.com, network, transport, adrian, delphij, decui_microsoft.com, honzhan_microsoft.com, howard0su_gmail.com, glebius Cc: freebsd-net-list [-- Attachment #2 --] diff --git a/sys/netinet/tcp_lro.h b/sys/netinet/tcp_lro.h --- a/sys/netinet/tcp_lro.h +++ b/sys/netinet/tcp_lro.h @@ -79,6 +79,7 @@ int lro_flushed; int lro_bad_csum; int lro_cnt; + int lro_hiwat; struct lro_head lro_active; struct lro_head lro_free; diff --git a/sys/netinet/tcp_lro.c b/sys/netinet/tcp_lro.c --- a/sys/netinet/tcp_lro.c +++ b/sys/netinet/tcp_lro.c @@ -77,6 +77,7 @@ lc->lro_queued = 0; lc->lro_flushed = 0; lc->lro_cnt = 0; + lc->lro_hiwat = 65535; SLIST_INIT(&lc->lro_free); SLIST_INIT(&lc->lro_active); @@ -501,7 +502,7 @@ } /* Flush now if appending will result in overflow. */ - if (le->p_len > (65535 - tcp_data_len)) { + if (le->p_len > (lc->lro_hiwat - tcp_data_len)) { SLIST_REMOVE(&lc->lro_active, le, lro_entry, next); tcp_lro_flush(lc, le); break; @@ -559,7 +560,7 @@ * If a possible next full length packet would cause an * overflow, pro-actively flush now. */ - if (le->p_len > (65535 - lc->ifp->if_mtu)) { + if (le->p_len > (lc->lro_hiwat - lc->ifp->if_mtu)) { SLIST_REMOVE(&lc->lro_active, le, lro_entry, next); tcp_lro_flush(lc, le); } else
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