Date: Tue, 3 Apr 2018 19:24:04 -0600 From: Cy Schubert <Cy.Schubert@cschubert.com> To: Bryan Drewery <bdrewery@FreeBSD.org>, Peter Jeremy <peter@rulingia.com>, Jeff Roberson <jroberson@jroberson.net> Cc: FreeBSD current <freebsd-current@freebsd.org>, Andriy Gapon <avg@freebsd.org> Subject: RE: Strange ARC/Swap/CPU on yesterday's -CURRENT Message-ID: <20180404012404.643D51076@spqr.komquats.com>
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+1 However under certain circumstances it will release some memory. To reprodu= ce, when bsdtar unpacks some tarballs (when building certain ports) tar wil= l use 12 GB or more forcing ARC to release memory. BTW, I haven't stopped to grok whether the bsdtar issue is local to me or a= nother problem yet. --- Sent using a tiny phone keyboard. Apologies for any typos and autocorrect. Also, this old phone only supports top post. Apologies. Cy Schubert <Cy.Schubert@cschubert.com> or <cy@freebsd.org> The need of the many outweighs the greed of the few. --- -----Original Message----- From: Bryan Drewery Sent: 23/03/2018 17:23 To: Peter Jeremy; Jeff Roberson Cc: FreeBSD current; Andriy Gapon Subject: Re: Strange ARC/Swap/CPU on yesterday's -CURRENT On 3/20/2018 12:07 AM, Peter Jeremy wrote: >=20 > On 2018-Mar-11 10:43:58 -1000, Jeff Roberson <jroberson@jroberson.net> wr= ote: >> Also, if you could try going back to r328953 or r326346 and let me know = if=20 >> the problem exists in either. That would be very helpful. If anyone is= =20 >> willing to debug this with me contact me directly and I will send some=20 >> test patches or debugging info after you have done the above steps. >=20 > I ran into this on 11-stable and tracked it to r326619 (MFC of r325851). > I initially got around the problem by reverting that commit but either > it or something very similar is still present in 11-stable r331053. >=20 > I've seen it in my main server (32GB RAM) but haven't managed to reproduc= e > it in smaller VBox guests - one difficulty I faced was artificially filli= ng > ARC. >=20 Looking at the ARC change you referred to from r325851 https://reviews.freebsd.org/D12163, I am convinced that ARC backpressure is completely broken. On my 78GB RAM system with ARC limited to 40GB and doing a poudriere build of all LLVM and GCC packages at once in tmpfs I can get swap up near 50GB and yet the ARC remains at 40GB through it all. It's always been slow to give up memory for package builds but it really seems broken right now. --=20 Regards, Bryan Drewery
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