Date: Mon, 10 Jul 2017 08:51:51 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Otac??lio <otacilio.neto@bsd.com.br> Cc: freebsd-current <freebsd-current@freebsd.org> Subject: Re: type of vm.stats.vm.v_vnodepgsin vm.stats.vm.v_swappgsin, vm.stats.vm.v_vnodepgsout vm.stats.vm.v_swappgsout on AMD64 r320730 Message-ID: <20170710055151.GL1935@kib.kiev.ua> In-Reply-To: <1c37db96-7cd2-91c9-011c-967a32a97f05@bsd.com.br> References: <1c37db96-7cd2-91c9-011c-967a32a97f05@bsd.com.br>
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On Sun, Jul 09, 2017 at 11:15:18PM -0300, Otac??lio wrote: > Dears > > I'm the maintainer of xosview and I'm debugging rather weird behavior > from it in the latest FreeBSD 12 revisions (12.0-CURRENT #0 r320730 > AMD64) . The problem is occurring on the lines responsible for > collecting statistics about paging. These lines follow: > > If (pageinfo) { > Pageinfo [0] = (uint64_t) vm.v_vnodepgsin + (uint64_t) vm.v_swappgsin; Why these casts are needed ? What is the type of vm.v_vnodepgsin ? > Pageinfo [1] = (uint64_t) vm.v_vnodepgsout + (uint64_t) vm.v_swappgsout; > } > > This code works on FreeBSD 11 and until a short time ago it works at 12. > But now it returns extremely large values ??????when interpreted as 64-bit > values. A debugging has shown that for this sysctl call the following > values ??????are returned in the terminal: > sysctl vm.stats.vm.v_vnodepgsin vm.stats.vm.v_swappgsin > vm.stats.vm.v_vnodepgsout vm.stats.vm.v_swappgsout > Vm.stats.vm.v_vnodepgsin: 47432 > Vm.stats.vm.v_swappgsin: 0 > Vm.stats.vm.v_vnodepgsout: 19 > Vm.stats.vm.v_swappgsout: 0 > > While the code returns things like: > > Pageinf [0] = 34359785800; Pageinfo [1] = 140733193388051 > Pageinf [0] = 34359785800; Pageinfo [1] = 2678138638516092947 > > After some tests I found that if I change the code to use a typecast to > (uint32_t) then Xosview works correctly.: > If (pageinfo) { > Pageinfo [0] = (uint32_t) ((uint64_t) vm.v_vnodepgsin + (uint64_t) > vm.v_swappgsin); > Pageinfo [1] = (uint32_t) ((uint64_t) vm.v_vnodepgsout + (uint64_t) > vm.v_swappgsout); > } > > For me, it seems that some code in the kernel is storing values ??????as 32 > bits where it should be 64 bits. Is this behavior correct? Show the _exact_ code fragment that reads the MIBs values.
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