Date: Tue, 7 Jan 2020 16:30:32 -0700 From: Warner Losh <imp@bsdimp.com> To: Alexander Motin <mav@freebsd.org> Cc: src-committers <src-committers@freebsd.org>, svn-src-all <svn-src-all@freebsd.org>, svn-src-head <svn-src-head@freebsd.org> Subject: Re: svn commit: r356480 - head/sys/dev/nvme Message-ID: <CANCZdfq1Y684EJSOBs7tjyBPDpkMekjvauBFkg2KskxcPNX-wg@mail.gmail.com> In-Reply-To: <202001072310.007NAdmV011346@repo.freebsd.org> References: <202001072310.007NAdmV011346@repo.freebsd.org>
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On Tue, Jan 7, 2020 at 4:10 PM Alexander Motin <mav@freebsd.org> wrote: > Author: mav > Date: Tue Jan 7 23:10:38 2020 > New Revision: 356480 > URL: https://svnweb.freebsd.org/changeset/base/356480 > > Log: > Increate HMB limit from 1% to 5%. > > SSD capacity in laptops is growing faster then RAM size, so my original > guess seems too low on second thought. Hopefully nobody will build large > array of those crappy SSDs. > If they do, they will likely want to turn off host buffer support anyway, since it uses PCIe bandwidth and large arrays tend to oversubscribe the PCIe bus... Warner > MFC after: 2 weeks > X-MFC-with: 356474 > > Modified: > head/sys/dev/nvme/nvme_ctrlr.c > > Modified: head/sys/dev/nvme/nvme_ctrlr.c > > ============================================================================== > --- head/sys/dev/nvme/nvme_ctrlr.c Tue Jan 7 22:45:02 2020 > (r356479) > +++ head/sys/dev/nvme/nvme_ctrlr.c Tue Jan 7 23:10:38 2020 > (r356480) > @@ -881,8 +881,8 @@ nvme_ctrlr_hmb_alloc(struct nvme_controller *ctrlr) > int err, i; > uint64_t max; > > - /* Limit HMB to 1% of RAM size per device by default. */ > - max = (uint64_t)physmem * PAGE_SIZE / 100; > + /* Limit HMB to 5% of RAM size per device by default. */ > + max = (uint64_t)physmem * PAGE_SIZE / 20; > TUNABLE_UINT64_FETCH("hw.nvme.hmb_max", &max); > > min = (long long unsigned)ctrlr->cdata.hmmin * 4096; >
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