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From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
To: Shahaf Shuler <shahafs@mellanox.com>, thomas@monjalon.net
Cc: dev@dpdk.org, stable@dpdk.org, alejandro.lucero@netronome.com
Subject: Re: [dpdk-dev] [PATCH v2] mem: limit use of address hint
Date: Tue, 2 Apr 2019 17:13:05 +0100	[thread overview]
Message-ID: <0ccaf7f1-e10c-de6a-1219-76ce6e76119f@intel.com> (raw)
Message-ID: <20190402161305.yvmcYS4tMxEA32FcCRQwBAb1PQB7qJMWJYlGfi0od0I@z> (raw)
In-Reply-To: <20190331084348.4740-1-shahafs@mellanox.com>

On 31-Mar-19 9:43 AM, Shahaf Shuler wrote:
> patch[1] added an address hint as starting address for 64 bit systems in
> case an explicit base virtual address was not set by the user.
> 
> The justification for such hint was to help devices that work in VA
> mode and has a address range limitation to work smoothly with the eal
> memory subsystem.
> 
> While the base address value selected may work fine for the eal
> initialization, it easily breaks when trying to register external memory
> using rte_extmem_register API.
> 
> Trying to register anonymous memory on RH x86_64 machine took several
> minutes, during them the function eal_get_virtual_area repeatedly
> scanned for a good VA candidate.
> 
> The attempt to guess which VA address will be free for mapping will
> always result in not portable, error prone code:
> * different application may use different libraries along w/ DPDK. One
>    can never guess which library was called first and how much virtual
>    memory it consumed.
> * external memory can be registered at any time in the application run
>    time.
> 
> In order not to break the existing secondary process design, this patch
> only limits the max number of tries that will be done with the
> address hint.
> When the number of tries exceeds the threshold the code
> will use the suggested address from kernel.
> 
> Fixes: 1df21702873d ("mem: use address hint for mapping hugepages")
> Cc: stable@dpdk.org
> Cc: alejandro.lucero@netronome.com
> 
> [1] commit 1df21702873d ("mem: use address hint for mapping hugepages")
> 
> Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
> ---
> 
> On v2:
>   * instead of a complete remove of the hint limit the number of tries we allow.
> ---

LGTM

Tested-by: Anatoly Burakov <anatoly.burakov@intel.com>

We can always increase the number of tries later :)

-- 
Thanks,
Anatoly

  parent reply	other threads:[~2019-04-02 16:13 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-21 20:21 [dpdk-dev] [PATCH] mem: don't use address hint for mapping unless requested Shahaf Shuler
2019-03-21 20:21 ` Shahaf Shuler
2019-03-27  5:36 ` Shahaf Shuler
2019-03-27  5:36   ` Shahaf Shuler
2019-03-27 11:49 ` Burakov, Anatoly
2019-03-27 11:49   ` Burakov, Anatoly
2019-03-28  8:45   ` Shahaf Shuler
2019-03-28  8:45     ` Shahaf Shuler
2019-03-28 10:26     ` Burakov, Anatoly
2019-03-28 10:26       ` Burakov, Anatoly
2019-03-31  8:43 ` [dpdk-dev] [PATCH v2] mem: limit use of address hint Shahaf Shuler
2019-03-31  8:43   ` Shahaf Shuler
2019-04-02 16:13   ` Burakov, Anatoly [this message]
2019-04-02 16:13     ` Burakov, Anatoly
2019-04-02 17:23     ` Alejandro Lucero
2019-04-02 17:23       ` Alejandro Lucero
2019-04-03 17:22       ` [dpdk-dev] [dpdk-stable] " Thomas Monjalon
2019-04-03 17:22         ` Thomas Monjalon

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