Proses flush mengkonsumsi terlalu banyak CPU

Server adalah EC2 Instance, singkatan dari menyimpan file ke NAS (NFS) dari HTTPD.

Proses seperti flush-0: 32 mengkonsumsi lebih dari% 90 CPU dan rata-rata beban: 65,50, 64,02, 66,59.

Menurut grafik, itu meningkat setiap hari sementara rata-rata beban awal ~ 1,01, 2,02, 1,80 pada 4 core. Saya telah menambahkan Mesin Virtual serupa lainnya di bawah Load Balancer dan Penggunaan CPU-nya hanya sekitar% 6 ATM.

Apa sebenarnya yang dilakukan proses flush ini?

Mungkin kita harus mematikan cache atribut NFS jika klien hanya perlu menulis data?

Mungkinkah itu karena fragmentasi paket?

Berikut adalah beberapa statistik dari nfsstat -s -4:

=================================================================
Server 0:

Server rpc stats:
calls      badcalls   badauth    badclnt    xdrcall
715054137   0          0          0          0       

Server nfs v4:
null         compound     
993       0% 715053143 99% 

Server nfs v4 operations:
op0-unused   op1-unused   op2-future   access       close        commit       
0         0% 0         0% 0         0% 143229323  6% 78092765  3% 36693816  1% 
create       delegpurge   delegreturn  getattr      getfh        link         
3486926   0% 0         0% 0         0% 679872421 28% 158406682  6% 0         0% 
lock         lockt        locku        lookup       lookup_root  nverify      
0         0% 0         0% 0         0% 95872524  4% 0         0% 0         0% 
open         openattr     open_conf    open_dgrd    putfh        putpubfh     
78173920  3% 0         0% 46442107  1% 1668      0% 715044032 29% 0         0% 
putrootfh    read         readdir      readlink     remove       rename       
7110      0% 42081145  1% 9116904   0% 0         0% 7026      0% 1257      0% 
renew        restorefh    savefh       secinfo      setattr      setcltid     
14        0% 81591622  3% 81659244  3% 0         0% 21028018  0% 3244      0% 
setcltidconf verify       write        rellockowner bc_ctl       bind_conn    
3244      0% 0         0% 114086560  4% 0         0% 0         0% 0         0% 
exchange_id  create_ses   destroy_ses  free_stateid getdirdeleg  getdevinfo   
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
getdevlist   layoutcommit layoutget    layoutreturn secinfononam sequence     
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
set_ssv      test_stateid want_deleg   destroy_clid reclaim_comp 
0         0% 0         0% 0         0% 0         0% 0         0% 

=================================================================
Server 1:

Server rpc stats:
calls      badcalls   badauth    badclnt    xdrcall
307172153   0          0          0          0       

Server nfs v4:
null         compound     
427       0% 307171725 99% 

Server nfs v4 operations:
op0-unused   op1-unused   op2-future   access       close        commit       
0         0% 0         0% 0         0% 58451998  5% 32717934  3% 15557564  1% 
create       delegpurge   delegreturn  getattr      getfh        link         
1424670   0% 0         0% 0         0% 291829363 28% 67959378  6% 0         0% 
lock         lockt        locku        lookup       lookup_root  nverify      
0         0% 0         0% 0         0% 41790934  4% 0         0% 0         0% 
open         openattr     open_conf    open_dgrd    putfh        putpubfh     
32741459  3% 0         0% 18993781  1% 75        0% 307167167 30% 0         0% 
putrootfh    read         readdir      readlink     remove       rename       
3108      0% 18598329  1% 3892199   0% 0         0% 742       0% 2         0% 
renew        restorefh    savefh       secinfo      setattr      setcltid     
3         0% 34142743  3% 34166131  3% 0         0% 8963430   0% 1449      0% 
setcltidconf verify       write        rellockowner bc_ctl       bind_conn    
1449      0% 0         0% 54628017  5% 0         0% 0         0% 0         0% 
exchange_id  create_ses   destroy_ses  free_stateid getdirdeleg  getdevinfo   
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
getdevlist   layoutcommit layoutget    layoutreturn secinfononam sequence     
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
set_ssv      test_stateid want_deleg   destroy_clid reclaim_comp 
0         0% 0         0% 0         0% 0         0% 0         0% 

=================================================================
Server 2:

Server rpc stats:
calls      badcalls   badauth    badclnt    xdrcall
53026598   0          0          0          0       

Server nfs v4:
null         compound     
89        0% 53026508 99% 

Server nfs v4 operations:
op0-unused   op1-unused   op2-future   access       close        commit       
0         0% 0         0% 0         0% 9605179   5% 5472897   3% 2633853   1% 
create       delegpurge   delegreturn  getattr      getfh        link         
231276    0% 0         0% 0         0% 50395149 28% 11903036  6% 0         0% 
lock         lockt        locku        lookup       lookup_root  nverify      
0         0% 0         0% 0         0% 7528324   4% 0         0% 0         0% 
open         openattr     open_conf    open_dgrd    putfh        putpubfh     
5477948   3% 0         0% 2760996   1% 15        0% 53025580 30% 0         0% 
putrootfh    read         readdir      readlink     remove       rename       
633       0% 3566001   2% 673466    0% 0         0% 11        0% 0         0% 
renew        restorefh    savefh       secinfo      setattr      setcltid     
2         0% 5704253   3% 5709223   3% 0         0% 1526967   0% 292       0% 
setcltidconf verify       write        rellockowner bc_ctl       bind_conn    
292       0% 0         0% 10439844  5% 0         0% 0         0% 0         0% 
exchange_id  create_ses   destroy_ses  free_stateid getdirdeleg  getdevinfo   
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
getdevlist   layoutcommit layoutget    layoutreturn secinfononam sequence     
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
set_ssv      test_stateid want_deleg   destroy_clid reclaim_comp 
0         0% 0         0% 0         0% 0         0% 0         0% 

=================================================================
Server 3:

Server rpc stats:
calls      badcalls   badauth    badclnt    xdrcall
63045403   0          0          0          0       

Server nfs v4:
null         compound     
121       0% 63045280 99% 

Server nfs v4 operations:
op0-unused   op1-unused   op2-future   access       close        commit       
0         0% 0         0% 0         0% 11504749  5% 6504139   3% 3119453   1% 
create       delegpurge   delegreturn  getattr      getfh        link         
271128    0% 0         0% 0         0% 59865633 28% 14058385  6% 0         0% 
lock         lockt        locku        lookup       lookup_root  nverify      
0         0% 0         0% 0         0% 8852565   4% 0         0% 0         0% 
open         openattr     open_conf    open_dgrd    putfh        putpubfh     
6521385   3% 0         0% 3365913   1% 15        0% 63043988 30% 0         0% 
putrootfh    read         readdir      readlink     remove       rename       
874       0% 4209822   2% 791702    0% 0         0% 6         0% 0         0% 
renew        restorefh    savefh       secinfo      setattr      setcltid     
9         0% 6775367   3% 6792509   3% 0         0% 1811226   0% 409       0% 
setcltidconf verify       write        rellockowner bc_ctl       bind_conn    
409       0% 0         0% 12368747  5% 0         0% 0         0% 0         0% 
exchange_id  create_ses   destroy_ses  free_stateid getdirdeleg  getdevinfo   
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
getdevlist   layoutcommit layoutget    layoutreturn secinfononam sequence     
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
set_ssv      test_stateid want_deleg   destroy_clid reclaim_comp 
0         0% 0         0% 0         0% 0         0% 0         0% 

=================================================================
Server 4:

Server rpc stats:
calls      badcalls   badauth    badclnt    xdrcall
817288490   0          0          0          0       

Server nfs v4:
null         compound     
1204      0% 817287285 99% 

Server nfs v4 operations:
op0-unused   op1-unused   op2-future   access       close        commit       
0         0% 0         0% 0         0% 164320609  6% 89471711  3% 42448842  1% 
create       delegpurge   delegreturn  getattr      getfh        link         
4101436   0% 0         0% 0         0% 778155935 28% 180629867  6% 0         0% 
lock         lockt        locku        lookup       lookup_root  nverify      
0         0% 0         0% 0         0% 109104313  4% 0         0% 0         0% 
open         openattr     open_conf    open_dgrd    putfh        putpubfh     
89598740  3% 0         0% 53534516  1% 9727      0% 817288175 29% 0         0% 
putrootfh    read         readdir      readlink     remove       rename       
8020      0% 46348481  1% 10773529  0% 0         0% 100880    0% 12342     0% 
renew        restorefh    savefh       secinfo      setattr      setcltid     
80        0% 93709338  3% 93712518  3% 0         0% 24303185  0% 3352      0% 
setcltidconf verify       write        rellockowner bc_ctl       bind_conn    
3352      0% 0         0% 127464001  4% 0         0% 0         0% 0         0% 
exchange_id  create_ses   destroy_ses  free_stateid getdirdeleg  getdevinfo   
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
getdevlist   layoutcommit layoutget    layoutreturn secinfononam sequence     
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
set_ssv      test_stateid want_deleg   destroy_clid reclaim_comp 
0         0% 0         0% 0         0% 0         0% 0         0% 

=================================================================
Server 5:

Server rpc stats:
calls      badcalls   badauth    badclnt    xdrcall
804660319   0          0          0          0       

Server nfs v4:
null         compound     
1204      0% 804659114 99% 

Server nfs v4 operations:
op0-unused   op1-unused   op2-future   access       close        commit       
0         0% 0         0% 0         0% 161331719  6% 88318366  3% 41571552  1% 
create       delegpurge   delegreturn  getattr      getfh        link         
4090384   0% 0         0% 0         0% 764533960 28% 177969216  6% 0         0% 
lock         lockt        locku        lookup       lookup_root  nverify      
0         0% 0         0% 0         0% 107385644  4% 0         0% 0         0% 
open         openattr     open_conf    open_dgrd    putfh        putpubfh     
88321805  3% 0         0% 54307425  2% 444       0% 804647492 29% 0         0% 
putrootfh    read         readdir      readlink     remove       rename       
8353      0% 45980723  1% 10410930  0% 0         0% 88471     0% 440       0% 
renew        restorefh    savefh       secinfo      setattr      setcltid     
21        0% 92410970  3% 92412629  3% 0         0% 23733174  0% 3688      0% 
setcltidconf verify       write        rellockowner bc_ctl       bind_conn    
3688      0% 0         0% 125268800  4% 0         0% 0         0% 0         0% 
exchange_id  create_ses   destroy_ses  free_stateid getdirdeleg  getdevinfo   
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
getdevlist   layoutcommit layoutget    layoutreturn secinfononam sequence     
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
set_ssv      test_stateid want_deleg   destroy_clid reclaim_comp 
0         0% 0         0% 0         0% 0         0% 0         0% 

=================================================================
Server 6:

Server rpc stats:
calls      badcalls   badauth    badclnt    xdrcall
795385017   0          0          0          0       

Server nfs v4:
null         compound     
1204      0% 795383812 99% 

Server nfs v4 operations:
op0-unused   op1-unused   op2-future   access       close        commit       
0         0% 0         0% 0         0% 158633282  5% 87331357  3% 41400927  1% 
create       delegpurge   delegreturn  getattr      getfh        link         
4080179   0% 0         0% 0         0% 756063664 28% 176355823  6% 0         0% 
lock         lockt        locku        lookup       lookup_root  nverify      
0         0% 0         0% 0         0% 106692513  4% 0         0% 0         0% 
open         openattr     open_conf    open_dgrd    putfh        putpubfh     
87333398  3% 0         0% 53591273  2% 187       0% 795371861 29% 0         0% 
putrootfh    read         readdir      readlink     remove       rename       
8367      0% 45030006  1% 10352133  0% 0         0% 80473     0% 151       0% 
renew        restorefh    savefh       secinfo      setattr      setcltid     
28        0% 91411943  3% 91413728  3% 0         0% 23629833  0% 3707      0% 
setcltidconf verify       write        rellockowner bc_ctl       bind_conn    
3707      0% 0         0% 124033436  4% 0         0% 0         0% 0         0% 
exchange_id  create_ses   destroy_ses  free_stateid getdirdeleg  getdevinfo   
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
getdevlist   layoutcommit layoutget    layoutreturn secinfononam sequence     
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
set_ssv      test_stateid want_deleg   destroy_clid reclaim_comp 
0         0% 0         0% 0         0% 0         0% 0         0% 

=================================================================
Server 7:

Server rpc stats:
calls      badcalls   badauth    badclnt    xdrcall
801916264   0          0          0          0       

Server nfs v4:
null         compound     
1204      0% 801915059 99% 

Server nfs v4 operations:
op0-unused   op1-unused   op2-future   access       close        commit       
0         0% 0         0% 0         0% 161888929  6% 88285947  3% 41212864  1% 
create       delegpurge   delegreturn  getattr      getfh        link         
4069479   0% 0         0% 0         0% 762072130 28% 177131560  6% 0         0% 
lock         lockt        locku        lookup       lookup_root  nverify      
0         0% 0         0% 0         0% 106437411  3% 0         0% 0         0% 
open         openattr     open_conf    open_dgrd    putfh        putpubfh     
88288337  3% 0         0% 54779036  2% 191       0% 801903449 29% 0         0% 
putrootfh    read         readdir      readlink     remove       rename       
8225      0% 45488312  1% 10259565  0% 0         0% 76243     0% 177       0% 
renew        restorefh    savefh       secinfo      setattr      setcltid     
4         0% 92355900  3% 92357993  3% 0         0% 23515286  0% 3558      0% 
setcltidconf verify       write        rellockowner bc_ctl       bind_conn    
3558      0% 0         0% 123741908  4% 0         0% 0         0% 0         0% 
exchange_id  create_ses   destroy_ses  free_stateid getdirdeleg  getdevinfo   
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
getdevlist   layoutcommit layoutget    layoutreturn secinfononam sequence     
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
set_ssv      test_stateid want_deleg   destroy_clid reclaim_comp 
0         0% 0         0% 0         0% 0         0% 0         0% 

=================================================================
Server 8:

Server rpc stats:
calls      badcalls   badauth    badclnt    xdrcall
804732833   1          1          0          0       

Server nfs v4:
null         compound     
1204      0% 804731628 99% 

Server nfs v4 operations:
op0-unused   op1-unused   op2-future   access       close        commit       
0         0% 0         0% 0         0% 161428939  6% 88340891  3% 41568432  1% 
create       delegpurge   delegreturn  getattr      getfh        link         
4085332   0% 0         0% 0         0% 764396486 28% 177796853  6% 0         0% 
lock         lockt        locku        lookup       lookup_root  nverify      
0         0% 0         0% 0         0% 107176837  3% 0         0% 0         0% 
open         openattr     open_conf    open_dgrd    putfh        putpubfh     
88342790  3% 0         0% 54344886  2% 187       0% 804720008 29% 0         0% 
putrootfh    read         readdir      readlink     remove       rename       
8226      0% 46219141  1% 10381361  0% 0         0% 83380     0% 160       0% 
renew        restorefh    savefh       secinfo      setattr      setcltid     
0         0% 92426602  3% 92428282  3% 0         0% 23736349  0% 3554      0% 
setcltidconf verify       write        rellockowner bc_ctl       bind_conn    
3554      0% 0         0% 125088530  4% 0         0% 0         0% 0         0% 
exchange_id  create_ses   destroy_ses  free_stateid getdirdeleg  getdevinfo   
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
getdevlist   layoutcommit layoutget    layoutreturn secinfononam sequence     
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
set_ssv      test_stateid want_deleg   destroy_clid reclaim_comp 
0         0% 0         0% 0         0% 0         0% 0         0% 

=================================================================
Server 9:

Server rpc stats:
calls      badcalls   badauth    badclnt    xdrcall
800961003   0          0          0          0       

Server nfs v4:
null         compound     
1204      0% 800959798 99% 

Server nfs v4 operations:
op0-unused   op1-unused   op2-future   access       close        commit       
0         0% 0         0% 0         0% 161394704  6% 88264733  3% 41642226  1% 
create       delegpurge   delegreturn  getattr      getfh        link         
4098314   0% 0         0% 0         0% 761225542 28% 172733291  6% 0         0% 
lock         lockt        locku        lookup       lookup_root  nverify      
0         0% 0         0% 0         0% 102217363  3% 0         0% 0         0% 
open         openattr     open_conf    open_dgrd    putfh        putpubfh     
88272429  3% 0         0% 53937975  2% 467       0% 800948292 30% 0         0% 
putrootfh    read         readdir      readlink     remove       rename       
8312      0% 45893437  1% 10409370  0% 0         0% 83127     0% 478       0% 
renew        restorefh    savefh       secinfo      setattr      setcltid     
35        0% 92369729  3% 92371221  3% 0         0% 23772628  0% 3637      0% 
setcltidconf verify       write        rellockowner bc_ctl       bind_conn    
3637      0% 0         0% 124997490  4% 0         0% 0         0% 0         0% 
exchange_id  create_ses   destroy_ses  free_stateid getdirdeleg  getdevinfo   
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
getdevlist   layoutcommit layoutget    layoutreturn secinfononam sequence     
0         0% 0         0% 0         0% 0         0% 0         0% 0         0% 
set_ssv      test_stateid want_deleg   destroy_clid reclaim_comp 
0         0% 0         0% 0         0% 0         0% 0         0%

linux amazon-ec2 linux-kernel

— Roman Newaza
sumber

Seberapa banyak?

— Fred Foo

karena pertanyaannya adalah tentang bug kernel yang melaporkan versi kernel akan membantu.

— Dmitri Chubarov

proses flush bertanggung jawab untuk mengelola penulisan kembali halaman-halaman kotor ke sistem berkas asalnya. Mereka seharusnya tidak menggunakan banyak CPU; sebagian besar waktu mereka dihabiskan menunggu disk (atau jaringan untuk NFS dan sejenisnya). Jika Anda melihat penggunaan CPU yang tinggi dari proses flush, itu mungkin bug kernel - coba reboot, ini akan menghapus status.

— omong kosong
sumber

Hai! Apa itu halaman kotor? Ya, saya baru saja menghentikan Instance yang gagal dan yang lainnya beroperasi secara normal ATM.

— Roman Newaza

Halaman kotor adalah bagian dari file yang di-cache dalam memori, telah dimodifikasi dalam memori oleh beberapa proses, tetapi belum ditulis kembali ke disk. Biasanya penulisan ini terjadi di latar belakang, kecuali jika jumlah halaman kotor terlalu tinggi, memori kosong terlalu rendah, atau program secara eksplisit bertanya - ketika penulisan terjadi di latar belakang, tugas flush untuk benar-benar memicu penulisan ini.

— bdonlan

bagaimana jika saya menjalankan echo 3 > /proc/sys/vm/drop_cachesflush pagecache, dentries dan inode?

— Roman Newaza

@RomanNewaza ini hanya akan menjatuhkan cache yang tidak terkunci atau kotor. siram biasanya tidak melakukan apa-apa dengan cache yang tidak kotor, jadi saya ragu itu akan membuat perbedaan (dan ini akan sangat merusak kinerja pada server sampai cache kembali hangat)

— bdonlan

Saya melihat. Sepertinya masalah telah hilang setelah peningkatan kernel.

— Roman Newaza