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From: Peter Xu <peterx@redhat.com>
To: "Marc-André Lureau" <marcandre.lureau@redhat.com>
Cc: "David Hildenbrand" <david@kernel.org>,
	qemu-devel@nongnu.org, "Ben Chaney" <bchaney@akamai.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"Cédric Le Goater" <clg@redhat.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Alex Williamson" <alex@shazbot.org>,
	"Fabiano Rosas" <farosas@suse.de>,
	"Philippe Mathieu-Daudé" <philmd@linaro.org>,
	kvm@vger.kernel.org, "Mark Kanda" <mark.kanda@oracle.com>
Subject: Re: [PATCH v3 09/15] system/ram-discard-manager: implement replay via is_populated iteration
Date: Tue, 3 Mar 2026 15:27:00 -0500	[thread overview]
Message-ID: <aadEFOLPsRjWTcfX@x1.local> (raw)
In-Reply-To: <CAMxuvazwmjjpnpsWpOd_=HcS-6ynpVjAw2u3R=VuE=Lhg=AnKw@mail.gmail.com>

On Tue, Mar 03, 2026 at 11:47:52AM +0100, Marc-André Lureau wrote:
> We can still iterate with 2M granularity after this patch. However, it
> may be less effective than iterating using find_next_bit(). Whether
> this is noticeable remains to be seen.

IIUC when in extreme scattered cases the results should be similar, say,
when the bitmap (2M for each bit) is 10101010....10101b. OTOH the worst
case scenario here is when e.g. the whole region is fully populated.

So.. if we have any concern, maybe we could run a VFIO population test on
non-CoCo, before or after this patch, having the whole region requested
available (so a bitmap with 111111111....111111b).

Thanks,

-- 
Peter Xu


  reply	other threads:[~2026-03-03 20:27 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-26 13:59 [PATCH v3 00/15] Make RamDiscardManager work with multiple sources marcandre.lureau
2026-02-26 13:59 ` [PATCH v3 01/15] system/rba: use DIV_ROUND_UP marcandre.lureau
2026-03-03 18:57   ` Peter Xu
2026-02-26 13:59 ` [PATCH v3 02/15] memory: drop RamDiscardListener::double_discard_supported marcandre.lureau
2026-02-26 15:58   ` David Hildenbrand
2026-03-03 18:57   ` Peter Xu
2026-02-26 13:59 ` [PATCH v3 03/15] virtio-mem: use warn_report_err_once() marcandre.lureau
2026-02-26 15:57   ` David Hildenbrand
2026-03-03 18:58   ` Peter Xu
2026-02-26 13:59 ` [PATCH v3 04/15] system/memory: minor doc fix marcandre.lureau
2026-02-26 15:58   ` David Hildenbrand
2026-03-03 18:59   ` Peter Xu
2026-02-26 13:59 ` [PATCH v3 05/15] kvm: replace RamDicardManager by the RamBlockAttribute marcandre.lureau
2026-03-03 18:59   ` Peter Xu
2026-03-04  9:09   ` Chenyi Qiang
2026-02-26 13:59 ` [PATCH v3 06/15] system/memory: split RamDiscardManager into source and manager marcandre.lureau
2026-03-03 19:45   ` Peter Xu
2026-03-04  9:51   ` Chenyi Qiang
2026-02-26 13:59 ` [PATCH v3 07/15] system/memory: move RamDiscardManager to separate compilation unit marcandre.lureau
2026-03-03 19:47   ` Peter Xu
2026-02-26 13:59 ` [PATCH v3 08/15] system/memory: constify section arguments marcandre.lureau
2026-03-03 19:48   ` Peter Xu
2026-02-26 13:59 ` [PATCH v3 09/15] system/ram-discard-manager: implement replay via is_populated iteration marcandre.lureau
2026-02-26 16:01   ` David Hildenbrand
2026-03-03 10:47     ` Marc-André Lureau
2026-03-03 20:27       ` Peter Xu [this message]
2026-02-26 13:59 ` [PATCH v3 10/15] virtio-mem: remove replay_populated/replay_discarded implementation marcandre.lureau
2026-02-26 13:59 ` [PATCH v3 11/15] system/ram-discard-manager: drop replay from source interface marcandre.lureau
2026-02-26 13:59 ` [PATCH v3 12/15] system/memory: implement RamDiscardManager multi-source aggregation marcandre.lureau
2026-03-03 21:16   ` Peter Xu
2026-02-26 13:59 ` [PATCH v3 13/15] system/physmem: destroy ram block attributes before RCU-deferred reclaim marcandre.lureau
2026-03-03 21:31   ` Peter Xu
2026-02-26 13:59 ` [PATCH v3 14/15] system/memory: add RamDiscardManager reference counting and cleanup marcandre.lureau
2026-03-03 21:33   ` Peter Xu
2026-02-26 14:00 ` [PATCH v3 15/15] tests: add unit tests for RamDiscardManager multi-source aggregation marcandre.lureau
2026-03-03 21:28 ` [PATCH v3 00/15] Make RamDiscardManager work with multiple sources Peter Xu
2026-03-03 22:33   ` Marc-André Lureau
2026-03-09 18:25 ` Peter Xu
2026-03-10  2:35 ` Chenyi Qiang
2026-03-10 16:09   ` Marc-André Lureau
2026-03-11  7:17     ` Chenyi Qiang
2026-03-11 14:12       ` Marc-André Lureau

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