Re: systat -vm output showing negative total virtual memory

[Ruslan Ermilov]

On Thu, Nov 16, 2006 at 11:55:09AM +0100, Ulrich Spoerlein wrote:
> Hi all,
> 
> this is on a two week old RELENG_6. The machine has 4GB RAM,  SMP
> 
> CPU: Intel(R) Xeon(TM) CPU 3.00GHz (3012.12-MHz 686-class CPU)
>  Origin = "GenuineIntel"  Id = 0xf43  Stepping = 3
> Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUS
> H,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
>  Features2=0x641d<SSE3,RSVD2,MON,DS_CPL,CNTX-ID,CX16,<b14>>
>  AMD Features=0x20100000<NX,LM>
> real memory  = 3489071104 (3327 MB)
> avail memory = 3414265856 (3256 MB)
> ACPI APIC Table: <PTLTD          APIC  >
> FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
> cpu0 (BSP): APIC ID:  0
> cpu1 (AP): APIC ID:  6
> 
> 
> Mem:KB    REAL            VIRTUAL                     VN PAGER  SWAP PAGER
>        Tot   Share      Tot    Share    Free         in  out     in  out
> Act 1198620  115040  1480676   289860  153004 count
> All 3330652  116920 -956751k   293960         pages
> 
> vm.vmtotal has this to say
> System wide totals computed every five seconds: (values in kilobytes)
> ===============================================
> Processes:              (RUNQ: 3 Disk Wait: 1 Page Wait: 1 Sleep: 40)
> Virtual Memory:         (Total: 815944K, Active 355288K)
> Real Memory:            (Total: 2558540K Active 150424K)
> Shared Virtual Memory:  (Total: 11460K Active: 7856K)
> Shared Real Memory:     (Total: 6916K Active: 5044K)
> Free Memory Pages:      890092K
> 
If my reading of the sys/vm/vm_meter.c code is correct, then
all this is wrong; t_vm, t_avm, t_vmshr, and t_avmshr are all
in bytes (here's a snippet from vm_meter.c):

:                 totalp->t_vm += object->size;
:                 totalp->t_rm += object->resident_page_count;
:                 if (object->flags & OBJ_ACTIVE) {
:                         totalp->t_avm += object->size;
:                         totalp->t_arm += object->resident_page_count;
:                 }
:                 if (object->shadow_count > 1) {
:                         /* shared object */
:                         totalp->t_vmshr += object->size;
:                         totalp->t_rmshr += object->resident_page_count;
:                         if (object->flags & OBJ_ACTIVE) {
:                                 totalp->t_avmshr += object->size;
:                                 totalp->t_armshr += 
object->resident_page_count;
:                         }
:                 }

sysctl(8) knows that t_vm is in bytes, but for the other stats
it thinks they are in pages.  "systat -vm" thinks they are all
in bytes.  Here's a fix:

%%%
Index: sbin/sysctl/sysctl.c
===================================================================
RCS file: /home/ncvs/src/sbin/sysctl/sysctl.c,v
retrieving revision 1.67.2.7
diff -u -p -r1.67.2.7 sysctl.c
--- sbin/sysctl/sysctl.c        8 Sep 2006 09:45:35 -0000       1.67.2.7
+++ sbin/sysctl/sysctl.c        16 Nov 2006 14:51:18 -0000
@@ -395,14 +395,14 @@ S_vmtotal(int l2, void *p)
            "%hu Sleep: %hu)\n",
            v->t_rq, v->t_dw, v->t_pw, v->t_sl);
        printf(
-           "Virtual Memory:\t\t(Total: %luK, Active %lldK)\n",
+           "Virtual Memory:\t\t(Total: %luK, Active %luK)\n",
            (unsigned long)v->t_vm / 1024,
-           (long long)v->t_avm * pageKilo);
+           (unsigned long)v->t_avm / 1024);
        printf("Real Memory:\t\t(Total: %lldK Active %lldK)\n",
            (long long)v->t_rm * pageKilo, (long long)v->t_arm * pageKilo);
-       printf("Shared Virtual Memory:\t(Total: %lldK Active: %lldK)\n",
-           (long long)v->t_vmshr * pageKilo,
-           (long long)v->t_avmshr * pageKilo);
+       printf("Shared Virtual Memory:\t(Total: %luK Active: %luK)\n",
+           (unsigned long)v->t_vmshr / 1024,
+           (unsigned long)v->t_avmshr / 1024);
        printf("Shared Real Memory:\t(Total: %lldK Active: %lldK)\n",
            (long long)v->t_rmshr * pageKilo,
            (long long)v->t_armshr * pageKilo);
Index: usr.bin/systat/vmstat.c
===================================================================
RCS file: /home/ncvs/src/usr.bin/systat/vmstat.c,v
retrieving revision 1.60.2.1
diff -u -p -r1.60.2.1 vmstat.c
--- usr.bin/systat/vmstat.c     21 Mar 2006 20:49:50 -0000      1.60.2.1
+++ usr.bin/systat/vmstat.c     16 Nov 2006 14:55:32 -0000
@@ -475,12 +475,12 @@ showkre()
 #define pgtokb(pg)     ((pg) * (s.v_page_size / 1024))
        putint(pgtokb(total.t_arm), MEMROW + 2, MEMCOL + 3, 8);
        putint(pgtokb(total.t_armshr), MEMROW + 2, MEMCOL + 11, 8);
-       putint(pgtokb(total.t_avm), MEMROW + 2, MEMCOL + 19, 9);
-       putint(pgtokb(total.t_avmshr), MEMROW + 2, MEMCOL + 28, 9);
+       putint(total.t_avm/1024, MEMROW + 2, MEMCOL + 19, 9);
+       putint(total.t_avmshr/1024, MEMROW + 2, MEMCOL + 28, 9);
        putint(pgtokb(total.t_rm), MEMROW + 3, MEMCOL + 3, 8);
        putint(pgtokb(total.t_rmshr), MEMROW + 3, MEMCOL + 11, 8);
-       putint(pgtokb(total.t_vm), MEMROW + 3, MEMCOL + 19, 9);
-       putint(pgtokb(total.t_vmshr), MEMROW + 3, MEMCOL + 28, 9);
+       putint(total.t_vm/1024, MEMROW + 3, MEMCOL + 19, 9);
+       putint(total.t_vmshr/1024, MEMROW + 3, MEMCOL + 28, 9);
        putint(pgtokb(total.t_free), MEMROW + 2, MEMCOL + 37, 8);
        putint(total.t_rq - 1, PROCSROW + 1, PROCSCOL + 3, 3);
        putint(total.t_pw, PROCSROW + 1, PROCSCOL + 6, 3);
%%%


Cheers,
-- 
Ruslan Ermilov
[EMAIL PROTECTED]
FreeBSD committer

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