On 26/03/2017 11:21 AM, Tariq Toukan wrote:
On 23/03/2017 4:51 PM, Mel Gorman wrote:
On Thu, Mar 23, 2017 at 02:43:47PM +0100, Jesper Dangaard Brouer wrote:
On Wed, 22 Mar 2017 23:40:04 +0000
Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> wrote:
On Wed, Mar 22, 2017 at 07:39:17PM +0200, Tariq Toukan wrote:
This modification may slow allocations from IRQ context slightly
but the
main gain from the per-cpu allocator is that it scales better for
allocations from multiple contexts. There is an implicit
assumption that
intensive allocations from IRQ contexts on multiple CPUs from a
single
NUMA node are rare
Hi Mel, Jesper, and all.
This assumption contradicts regular multi-stream traffic that is
naturally
handled
over close numa cores. I compared iperf TCP multistream (8 streams)
over CX4 (mlx5 driver) with kernels v4.10 (before this series) vs
kernel v4.11-rc1 (with this series).
I disabled the page-cache (recycle) mechanism to stress the page
allocator,
and see a drastic degradation in BW, from 47.5 G in v4.10 to 31.4 G in
v4.11-rc1 (34% drop).
I noticed queued_spin_lock_slowpath occupies 62.87% of CPU time.
Can you get the stack trace for the spin lock slowpath to confirm it's
from IRQ context?
AFAIK allocations happen in softirq. Argh and during review I missed
that in_interrupt() also covers softirq. To Mel, can we use a in_irq()
check instead?
(p.s. just landed and got home)
Glad to hear. Thanks for your suggestion.
Not built or even boot tested. I'm unable to run tests at the moment
Thanks Mel, I will test it soon.
Crashed in iperf single stream test:
[ 3974.123386] ------------[ cut here ]------------
[ 3974.128778] WARNING: CPU: 2 PID: 8754 at lib/list_debug.c:53
__list_del_entry_valid+0xa3/0xd0
[ 3974.138751] list_del corruption. prev->next should be
ffffea0040369c60, but was dead000000000100
[ 3974.149016] Modules linked in: netconsole nfsv3 nfs fscache dm_mirror
dm_region_hash dm_log dm_mod sb_edac edac_core x86_pkg_temp_thermal
coretemp i2c_diolan_u2c kvm irqbypass ipmi_si ipmi_devintf crc32_pclmul
iTCO_wdt ghash_clmulni_intel ipmi_msghandler dcdbas iTCO_vendor_support
sg pcspkr lpc_ich shpchp wmi mfd_core acpi_power_meter nfsd auth_rpcgss
nfs_acl lockd grace sunrpc binfmt_misc ip_tables mlx4_en sr_mod cdrom
sd_mod i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt
fb_sys_fops mlx5_core ttm tg3 ahci libahci mlx4_core drm libata ptp
megaraid_sas crc32c_intel i2c_core pps_core [last unloaded: netconsole]
[ 3974.212743] CPU: 2 PID: 8754 Comm: iperf Not tainted 4.11.0-rc2+ #30
[ 3974.220073] Hardware name: Dell Inc. PowerEdge R730/0H21J3, BIOS
1.5.4 10/002/2015
[ 3974.228974] Call Trace:
[ 3974.231925] <IRQ>
[ 3974.234405] dump_stack+0x63/0x8c
[ 3974.238355] __warn+0xd1/0xf0
[ 3974.241891] warn_slowpath_fmt+0x4f/0x60
[ 3974.246494] __list_del_entry_valid+0xa3/0xd0
[ 3974.251583] get_page_from_freelist+0x84c/0xb40
[ 3974.256868] ? napi_gro_receive+0x38/0x140
[ 3974.261666] __alloc_pages_nodemask+0xca/0x200
[ 3974.266866] mlx5e_alloc_rx_wqe+0x49/0x130 [mlx5_core]
[ 3974.272862] mlx5e_post_rx_wqes+0x84/0xc0 [mlx5_core]
[ 3974.278725] mlx5e_napi_poll+0xc7/0x450 [mlx5_core]
[ 3974.284409] net_rx_action+0x23d/0x3a0
[ 3974.288819] __do_softirq+0xd1/0x2a2
[ 3974.293054] irq_exit+0xb5/0xc0
[ 3974.296783] do_IRQ+0x51/0xd0
[ 3974.300353] common_interrupt+0x89/0x89
[ 3974.304859] RIP: 0010:free_hot_cold_page+0x228/0x280
[ 3974.310629] RSP: 0018:ffffc9000ea07c90 EFLAGS: 00000202 ORIG_RAX:
ffffffffffffffa8
[ 3974.319565] RAX: 0000000000000001 RBX: ffff88103f85f158 RCX:
ffffea0040369c60
[ 3974.327764] RDX: ffffea0040369c60 RSI: ffff88103f85f168 RDI:
ffffea0040369ca0
[ 3974.335961] RBP: ffffc9000ea07cc0 R08: ffff88103f85f168 R09:
00000000000005a8
[ 3974.344178] R10: 00000000000005a8 R11: 0000000000010468 R12:
ffffea0040369c80
[ 3974.352387] R13: ffff88103f85f168 R14: ffff88107ffdeb80 R15:
ffffea0040369ca0
[ 3974.360577] </IRQ>
[ 3974.363145] __put_page+0x34/0x40
[ 3974.367068] skb_release_data+0xca/0xe0
[ 3974.371575] skb_release_all+0x24/0x30
[ 3974.375984] __kfree_skb+0x12/0x20
[ 3974.380003] tcp_recvmsg+0x6ac/0xaf0
[ 3974.384251] inet_recvmsg+0x3c/0xa0
[ 3974.388394] sock_recvmsg+0x3d/0x50
[ 3974.392511] SYSC_recvfrom+0xd3/0x140
[ 3974.396826] ? handle_mm_fault+0xce/0x240
[ 3974.401535] ? SyS_futex+0x71/0x150
[ 3974.405653] SyS_recvfrom+0xe/0x10
[ 3974.409673] entry_SYSCALL_64_fastpath+0x1a/0xa9
[ 3974.415056] RIP: 0033:0x7f04ca9315bb
[ 3974.419309] RSP: 002b:00007f04c955de70 EFLAGS: 00000246 ORIG_RAX:
000000000000002d
[ 3974.428243] RAX: ffffffffffffffda RBX: 0000000000020000 RCX:
00007f04ca9315bb
[ 3974.436450] RDX: 0000000000020000 RSI: 00007f04bc0008f0 RDI:
0000000000000004
[ 3974.444653] RBP: 0000000000000000 R08: 0000000000000000 R09:
0000000000000000
[ 3974.452851] R10: 0000000000000000 R11: 0000000000000246 R12:
00007f04bc0008f0
[ 3974.461051] R13: 0000000000034ac8 R14: 00007f04bc020910 R15:
000000000001c480
[ 3974.469297] ---[ end trace 6fd472c9e1973d53 ]---
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6cbde310abed..f82225725bc1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2481,7 +2481,7 @@ void free_hot_cold_page(struct page *page, bool
cold)
unsigned long pfn = page_to_pfn(page);
int migratetype;
- if (in_interrupt()) {
+ if (in_irq()) {
__free_pages_ok(page, 0);
return;
}
@@ -2647,7 +2647,7 @@ static struct page *__rmqueue_pcplist(struct
zone *zone, int migratetype,
{
struct page *page;
- VM_BUG_ON(in_interrupt());
+ VM_BUG_ON(in_irq());
do {
if (list_empty(list)) {
@@ -2704,7 +2704,7 @@ struct page *rmqueue(struct zone *preferred_zone,
unsigned long flags;
struct page *page;
- if (likely(order == 0) && !in_interrupt()) {
+ if (likely(order == 0) && !in_irq()) {
page = rmqueue_pcplist(preferred_zone, zone, order,
gfp_flags, migratetype);
goto out;
--
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