From owner-freebsd-arm@freebsd.org Thu Aug 9 15:28:11 2018 Return-Path: Delivered-To: freebsd-arm@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id D030B106A1C9 for ; Thu, 9 Aug 2018 15:28:11 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: from mail-io0-x236.google.com (mail-io0-x236.google.com [IPv6:2607:f8b0:4001:c06::236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 5107F79FF5 for ; Thu, 9 Aug 2018 15:28:11 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: by mail-io0-x236.google.com with SMTP id z19-v6so5097550ioh.4 for ; Thu, 09 Aug 2018 08:28:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20150623.gappssmtp.com; s=20150623; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=WrbUYVSrvd9cwZTkv1c9MBfrIEqYjM95SywAYd7cw9I=; b=wt9ignCU5BRi1UfGNizDSCW10YpfuPtwwHiX/R1+mF7LqoTWKjGEL9zq5nmf31nnkF lee06Rz8wUG8J5gfFHVra8xTVUDrpqpXxKoLTmQ92yUyhjJ9bn2Ppp9WXrym9MVovzUh ShoL7sFBxm4YNgg4WfMiWToMh+rcHXi4PK/ASTfvIpjW4YmthYwcAVJclhrwgSsV7QOW A2+gLgBsvhkoqezZB6l4Vv3Djmt45EVjMLJSal83vNKpKQZISkPv7Il9Qn3cOgQo4lNP UR39MVOQ2UaFfsCoDuDpCCVjA72bBQN0vTiFxwmpT3R5TPMrkLDwh33UwYh6Dt3BXVEL kCjw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=WrbUYVSrvd9cwZTkv1c9MBfrIEqYjM95SywAYd7cw9I=; b=G89frOmQfqoES1LrSk+6SDSSUvV7OZ7p04C+VtLBb/CMsZxxjcisM89jcNMxO9f6Rc U+4+HtUjnSVe3W0/W5KY4d5sZjK9h4TpfX2UGDnmiXCNlXYIJVSFpngiFeFX3lROXblL d41jSFs0cJISXPFmho5MkPLUL+/BxdibXQCvwHYtWhSzaeRVPflco8Q/HgvaTaVDo786 WduSms9ppc3CkuPXy67k2eKPGDQxruJ7n5GyJPa/wuKmRcREVYRg5sUTDDDa/DWvdzo0 fgWQeD3XDrYTMcWS1BqAlkg0Z8hMdmtN4IR/st7Mgltvw9ItqkO9PjxqWYwc2hwh8mMK K+dg== X-Gm-Message-State: AOUpUlE6Srbyetn3WQepGjG4wtpyzOmOnv15jyYBgMtsRzZy9GBi6ml1 94WST1aMwoLzSQb9RhSYycMBVK1HEIyjLOlI5aUByezyPng= X-Google-Smtp-Source: AA+uWPx8IRgwJbSTH2wPEOr7V9qQnxd0OpHztaOw7N+IQP+SWZIy0uRfbHBIbv7QQNmplrm79z2+u9xSQ1JlKdrvojA= X-Received: by 2002:a6b:3902:: with SMTP id g2-v6mr2156544ioa.168.1533828490339; Thu, 09 Aug 2018 08:28:10 -0700 (PDT) MIME-Version: 1.0 Sender: wlosh@bsdimp.com Received: by 2002:a4f:381a:0:0:0:0:0 with HTTP; Thu, 9 Aug 2018 08:28:09 -0700 (PDT) X-Originating-IP: [2603:300b:6:5100:1052:acc7:f9de:2b6d] In-Reply-To: <20180809152152.GC68459@raichu> References: <20180801034511.GA96616@www.zefox.net> <201808010405.w7145RS6086730@donotpassgo.dyslexicfish.net> <6BFE7B77-A0E2-4FAF-9C68-81951D2F6627@yahoo.com> <20180802002841.GB99523@www.zefox.net> <20180802015135.GC99523@www.zefox.net> <20180806155837.GA6277@raichu> <20180808153800.GF26133@www.zefox.net> <20180808204841.GA19379@raichu> <20180809065648.GB30347@www.zefox.net> <20180809152152.GC68459@raichu> From: Warner Losh Date: Thu, 9 Aug 2018 09:28:09 -0600 X-Google-Sender-Auth: GwYJjP4HrUxuywHRQMKvjwCTeys Message-ID: Subject: Re: RPI3 swap experiments ["was killed: out of swap space" with: "v_free_count: 5439, v_inactive_count: 1"] To: Mark Johnston Cc: bob prohaska , "freebsd-arm@freebsd.org" Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.27 X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 09 Aug 2018 15:28:12 -0000 On Thu, Aug 9, 2018 at 9:21 AM, Mark Johnston wrote: > On Wed, Aug 08, 2018 at 11:56:48PM -0700, bob prohaska wrote: > > On Wed, Aug 08, 2018 at 04:48:41PM -0400, Mark Johnston wrote: > > > On Wed, Aug 08, 2018 at 08:38:00AM -0700, bob prohaska wrote: > > > > The patched kernel ran longer than default but OOMA still halted > buildworld around > > > > 13 MB. That's considerably farther than a default build world have > run but less than > > > > observed when setting vm.pageout_oom_seq=120 alone. Log files are at > > > > http://www.zefox.net/~fbsd/rpi3/swaptests/r337226M/ > 1gbsdflash_1gbusbflash/batchqueue/ > > > > > > > > Both changes are now in place and -j4 buildworld has been restarted. > > > > > > Looking through the gstat output, I'm seeing some pretty abysmal > average > > > write latencies for da0, the flash drive. I also realized that my > > > reference to r329882 lowering the pagedaemon sleep period was wrong - > > > things have been this way for much longer than that. Moreover, as you > > > pointed out, bumping oom_seq to a much larger value wasn't quite > > > sufficient. > > > > > > I'm curious as to what the worst case swap I/O latencies are in your > > > test, since the average latencies reported in your logs are high enough > > > to trigger OOM kills even with the increased oom_seq value. When the > > > current test finishes, could you try repeating it with this patch > > > applied on top? https://people.freebsd.org/~ > markj/patches/slow_swap.diff > > > That is, keep the non-default oom_seq setting and modification to > > > VM_BATCHQUEUE_SIZE, and apply this patch on top. It'll cause the > kernel > > > to print messages to the console under certain conditions, so a log of > > > console output will be interesting. > > > > The run finished with a panic, I've collected the logs and terminal > output at > > http://www.zefox.net/~fbsd/rpi3/swaptests/r337226M/ > 1gbsdflash_1gbusbflash/batchqueue/pageout120/slow_swap/ > > > > There seems to be a considerable discrepancy between the wait times > reported > > by the patch and the wait times reported by gstat in the first couple of > > occurrences. The fun begins at timestamp Wed Aug 8 21:26:03 PDT 2018 in > > swapscript.log. > > The reports of "waited for swap buffer" are especially bad: during those > periods, the laundry thread is blocked waiting for in-flight swap writes > to finish before sending any more. Because the system is generally > quite starved for clean pages that it can reuse, it's relying on swap > I/O to clean more. If that fails, the system eventually has no choice > but to start killing processes (where the time period corresponding to > "eventually" is determined by vm.pageout_oom_seq). > Based on these latencies, I think the system is behaving more or less as > expected from the VM's perspective. I do think the default oom_seq value > is too low and will get that addressed in 12.0. Yea. I think we need to take a more active role in managing latencies on some cards. Properly managed, they won't climb that high. Since there's no tagged queueing to these devices, there's an I/O depth of one. The default policy is to do them in order (since it's flash) which means that processes that machine-gun down requests swamp everybody else and do back-to-back-to-back writes which, at least for the few drives I have looked at in detail tends to induce pathological behavior. Warner