From: Paolo Bonzini <pbonzini@redhat.com>
To: Markus Armbruster <armbru@redhat.com>
Cc: qemu-devel@nongnu.org, quintela@redhat.com
Subject: [Qemu-devel] Re: [PATCH 16/28] migration: use global variable directly
Date: Thu, 24 Feb 2011 08:58:04 +0100 [thread overview]
Message-ID: <4D660F8C.3030406@redhat.com> (raw)
In-Reply-To: <m3k4gphps1.fsf@blackfin.pond.sub.org>
On 02/24/2011 08:09 AM, Markus Armbruster wrote:
> For completeness: a local variable may be necessary to convince the
> optimizer that the value doesn't change. Cases where this matters
> exist, but they're rare.
In particular, for non-pointers they're nonexistent if the variable is
static and you never use ¤t_migration, i.e. if the variable
doesn't escape.
If the above conditions are satisfied and you have a loop that never
"leaves" the C file, you could even see the compiler keep the variable
in a register for the whole duration of the loop and store the modified
change after the loop.
Paolo
next prev parent reply other threads:[~2011-02-24 7:58 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-23 21:47 [Qemu-devel] [PATCH v2 00/28] Refactor and cleanup migration code Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 01/28] migration: Make *start_outgoing_migration return FdMigrationState Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 02/28] migration: Use FdMigrationState instead of MigrationState when possible Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 03/28] migration: Fold MigrationState into FdMigrationState Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 04/28] migration: Rename FdMigrationState MigrationState Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 05/28] migration: Refactor MigrationState creation Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 06/28] migration: Make all posible migration functions static Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 07/28] migration: move migrate_create_state to do_migrate Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 08/28] migration: Check that migration is active before cancel it Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 09/28] migration: Introduce MIG_STATE_NONE Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 10/28] migration: Refactor and simplify error checking in migrate_fd_put_ready Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 11/28] migration: Introduce migrate_fd_completed() for consistenncy Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 12/28] migration: Our release callback was just free Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 13/28] migration: Remove get_status() accessor Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 14/28] migration: Remove migration cancel() callback Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 15/28] migration: Move exported functions to the end of the file Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 16/28] migration: use global variable directly Juan Quintela
2011-02-23 22:18 ` Anthony Liguori
2011-02-23 22:46 ` [Qemu-devel] " Juan Quintela
2011-02-23 23:04 ` Anthony Liguori
2011-02-23 23:07 ` Juan Quintela
2011-02-24 7:09 ` Markus Armbruster
2011-02-24 7:58 ` Paolo Bonzini [this message]
2011-02-23 21:47 ` [Qemu-devel] [PATCH 17/28] migration: another case of global variable assigned to local one Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 18/28] migration: convert current_migration from pointer to struct Juan Quintela
2011-02-23 22:19 ` Anthony Liguori
2011-02-23 22:50 ` [Qemu-devel] " Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 19/28] migration: Use bandwidth_limit directly Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 20/28] migration: Export a function that tells if the migration has finished correctly Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 21/28] migration: Make state definitions local Juan Quintela
2011-02-24 4:12 ` Yoshiaki Tamura
2011-02-24 9:01 ` [Qemu-devel] " Juan Quintela
2011-02-24 9:16 ` Yoshiaki Tamura
2011-02-23 21:47 ` [Qemu-devel] [PATCH 22/28] savevm: avoid qemu_savevm_state_iteate() to return 1 when qemu file has error Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 23/28] migration: add error handling to migrate_fd_put_notify() Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 24/28] migration: Don't use callback on file defining it Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 25/28] migration: propagate error correctly Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 26/28] migration: qemu_savevm_iterate has three return values Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 27/28] migration: If there is one error, it makes no sense to continue Juan Quintela
2011-02-23 21:47 ` [Qemu-devel] [PATCH 28/28] migration: make migration-{tcp, unix} consistent Juan Quintela
2011-04-02 7:54 ` [Qemu-devel] [PATCH v2 00/28] Refactor and cleanup migration code Yoshiaki Tamura
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