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| author |   Eric Dumazet <edumazet@google.com> | 2019-06-14 16:22:21 -0700 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2019-06-14 20:18:28 -0700 |
| commit | ce27ec60648d8e066227cb2f58b1d3d4f7253d08 (patch) | |
| tree | 220daaf7fb72acc2cfe6fab06c1ac0e0f4384157 /net/core | |
| parent | tcp: add tcp_tx_skb_cache sysctl (diff) | |
| download | linux-dev-ce27ec60648d8e066227cb2f58b1d3d4f7253d08.tar.xz linux-dev-ce27ec60648d8e066227cb2f58b1d3d4f7253d08.zip | |
net: add high_order_alloc_disable sysctl/static key
>From linux-3.7, (commit 5640f7685831 "net: use a per task frag
allocator") TCP sendmsg() has preferred using order-3 allocations.
While it gives good results for most cases, we had reports
that heavy uses of TCP over loopback were hitting a spinlock
contention in page allocations/freeing.
This commits adds a sysctl so that admins can opt-in
for order-0 allocations. Hopefully mm layer might optimize
order-3 allocations in the future since it could give us
a nice boost (see 8 lines of following benchmark)
The following benchmark shows a win when more than 8 TCP_STREAM
threads are running (56 x86 cores server in my tests)
for thr in {1..30}
do
sysctl -wq net.core.high_order_alloc_disable=0
T0=`./super_netperf $thr -H 127.0.0.1 -l 15`
sysctl -wq net.core.high_order_alloc_disable=1
T1=`./super_netperf $thr -H 127.0.0.1 -l 15`
echo $thr:$T0:$T1
done
1: 49979: 37267
2: 98745: 76286
3: 141088: 110051
4: 177414: 144772
5: 197587: 173563
6: 215377: 208448
7: 241061: 234087
8: 267155: 263373
9: 295069: 297402
10: 312393: 335213
11: 340462: 368778
12: 371366: 403954
13: 412344: 443713
14: 426617: 473580
15: 474418: 507861
16: 503261: 538539
17: 522331: 563096
18: 532409: 567084
19: 550824: 605240
20: 525493: 641988
21: 564574: 665843
22: 567349: 690868
23: 583846: 710917
24: 588715: 736306
25: 603212: 763494
26: 604083: 792654
27: 602241: 796450
28: 604291: 797993
29: 611610: 833249
30: 577356: 841062
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/sock.c | 4 | ||||
| -rw-r--r-- | net/core/sysctl_net_core.c | 7 |
2 files changed, 10 insertions, 1 deletions
diff --git a/net/core/sock.c b/net/core/sock.c index 2b3701958486..7f49392579a5 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2320,6 +2320,7 @@ static void sk_leave_memory_pressure(struct sock *sk) /* On 32bit arches, an skb frag is limited to 2^15 */ #define SKB_FRAG_PAGE_ORDER get_order(32768) +DEFINE_STATIC_KEY_FALSE(net_high_order_alloc_disable_key); /** * skb_page_frag_refill - check that a page_frag contains enough room @@ -2344,7 +2345,8 @@ bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t gfp) } pfrag->offset = 0; - if (SKB_FRAG_PAGE_ORDER) { + if (SKB_FRAG_PAGE_ORDER && + !static_branch_unlikely(&net_high_order_alloc_disable_key)) { /* Avoid direct reclaim but allow kswapd to wake */ pfrag->page = alloc_pages((gfp & ~__GFP_DIRECT_RECLAIM) | __GFP_COMP | __GFP_NOWARN | diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index 1a2685694abd..f9204719aeee 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -562,6 +562,13 @@ static struct ctl_table net_core_table[] = { .extra1 = &zero, .extra2 = &two, }, + { + .procname = "high_order_alloc_disable", + .data = &net_high_order_alloc_disable_key.key, + .maxlen = sizeof(net_high_order_alloc_disable_key), + .mode = 0644, + .proc_handler = proc_do_static_key, + }, { } }; |